How do i render the contents of a xamarin forms (portable) control in custom renderers?

This is my code so far (Works, but I can’t figure out the missing bit):

Shared project:

using System;
using Xamarin.Forms;

namespace Solvum.SiteTracker.Mobile.XamarinForms.Framework.Controls
{
public enum DrawerPosition
{
Left,
Right
}

public interface ISideDrawerNativeEventProxy
{
void RaiseSlideChanged(float percentage);
}

public class SideDrawer : Grid, ISideDrawerNativeEventProxy
{

public static BindableProperty DrawerSizeProperty = BindableProperty.Create<SideDrawer, MaxedPercentSize>(d => d.DrawerSize, new MaxedPercentSize(MaxedPercentSizeType.Width, 80, 400));

public MaxedPercentSize DrawerSize
{
get { return (MaxedPercentSize) GetValue(DrawerSizeProperty); }
set { SetValue(DrawerSizeProperty, value); }
}

public static BindableProperty IsOpenProperty = BindableProperty.Create<SideDrawer, bool>(d => d.IsOpen, default(bool));

public bool IsOpen
{
get { return (bool) GetValue(IsOpenProperty); }
set { SetValue(IsOpenProperty, value); }
}

public static BindableProperty DrawerPositionProperty = BindableProperty.Create<SideDrawer, DrawerPosition>(d => d.DrawerPosition, default(DrawerPosition));

public DrawerPosition DrawerPosition
{
get { return (DrawerPosition) GetValue(DrawerPositionProperty); }
set { SetValue(DrawerPositionProperty, value); }
}

public static BindableProperty MainContentProperty = BindableProperty.Create<SideDrawer, View>(d => d.MainContent, default(View));

public View MainContent
{
get { return (View) GetValue(MainContentProperty); }
set { SetValue(MainContentProperty, value); }
}

public static BindableProperty DrawerContentProperty = BindableProperty.Create<SideDrawer, View>(d => d.DrawerContent, default(View));

public View DrawerContent
{
get { return (View) GetValue(DrawerContentProperty); }
set { SetValue(DrawerContentProperty, value); }
}

public static BindableProperty DrawerLengthProperty = BindableProperty.Create<SideDrawer, int>(d => d.DrawerLength, default(int), defaultValueCreator: DrawerLengthDefault);

private static int DrawerLengthDefault(SideDrawer bindable)
{
return 300;
}

public int DrawerLength
{
get { return (int) GetValue(DrawerLengthProperty); }
set { SetValue(DrawerLengthProperty, value); }
}

public static BindableProperty IsContentTranslatedProperty = BindableProperty.Create<SideDrawer, bool>(d => d.IsContentTranslated, true);

public bool IsContentTranslated
{
get { return (bool) GetValue(IsContentTranslatedProperty); }
set { SetValue(IsContentTranslatedProperty, value); }
}

void ISideDrawerNativeEventProxy.RaiseSlideChanged(float percentage)
{
}
}
}

Android:

using System;
using System.ComponentModel;
using Android.Support.V4.Widget;
using Android.Views;
using Android.Widget;
using Solvum.SiteTracker.Mobile.XamarinForms.Droid.Controls.SideDrawer;
using Solvum.SiteTracker.Mobile.XamarinForms.Framework.Controls;
using Xamarin.Forms;
using Xamarin.Forms.Platform.Android;
using Android.Graphics;
using Application = Android.App.Application;
using Color = Android.Graphics.Color;
using RelativeLayout = Android.Widget.RelativeLayout;
using View = Android.Views.View;

[assembly: ExportRenderer(typeof(SideDrawer), typeof(SideDrawerRenderer))]
namespace Solvum.SiteTracker.Mobile.XamarinForms.Droid.Controls.SideDrawer
{
// public class SideDrawerRenderer : Xamarin.Forms.Platform.Android.AppCompat.ViewRenderer<Framework.Controls.SideDrawer, DrawerLayout>, DrawerLayout.IDrawerListener
public class SideDrawerRenderer : ViewRenderer<Framework.Controls.SideDrawer, DrawerLayout>, DrawerLayout.IDrawerListener
{
private DrawerLayout _nativeDrawerLayout;
private MarginLayoutParams _contentLayoutParameters;
private RelativeLayout _contentView;
private TextView _drawerView;

protected override void OnElementChanged(ElementChangedEventArgs<Framework.Controls.SideDrawer> e)
{
base.OnElementChanged(e);

if (this.Control == null)
{
InitializeNativeControl();
}
if (e.OldElement != null)
{
_nativeDrawerLayout.SetDrawerListener(null);
}
if (e.NewElement != null)
{
_nativeDrawerLayout.SetDrawerListener(this);
}
}

private void InitializeNativeControl()
{
_nativeDrawerLayout = new DrawerLayout(Context.ApplicationContext);
_nativeDrawerLayout.SetBackgroundColor(Element.BackgroundColor.ToAndroid());

_contentLayoutParameters = new MarginLayoutParams(LayoutParams.MatchParent, LayoutParams.MatchParent);
var layoutParamsDrawer = new DrawerLayout.LayoutParams(Element.DrawerLength, LinearLayout.LayoutParams.MatchParent);
layoutParamsDrawer.Gravity = GetDrawerGravity();

_drawerView = GetDrawerView(layoutParamsDrawer);
_contentView = GetContentView(_contentLayoutParameters);

// this one works, but i need the content from my forms property
var contentChild = new RelativeLayout(Context.ApplicationContext);
var contentChildLParams = new RelativeLayout.LayoutParams(300, 300);
contentChild.SetBackgroundColor(Color.Yellow);
_contentView.AddView(contentChild, contentChildLParams);

// i need to figure out how to make this work
// var contentRenderer = RendererFactory.GetRenderer(Element.MainContent);
// _contentView.AddView(contentRenderer.ViewGroup, new LayoutParams(LayoutParams.MatchParent, LayoutParams.MatchParent));

_nativeDrawerLayout.AddView(_drawerView);
_nativeDrawerLayout.AddView(_contentView);

SetNativeControl(_nativeDrawerLayout);
}

private int GetDrawerGravity()
{
switch (Element.DrawerPosition)
{
case DrawerPosition.Left:
return (int)GravityFlags.Start;
case DrawerPosition.Right:
return (int)GravityFlags.End;
default:
throw new ArgumentOutOfRangeException();
}
}

private RelativeLayout GetContentView(LayoutParams layoutParameters)
{
var view = new RelativeLayout(Context.ApplicationContext);
view.LayoutParameters = layoutParameters;
view.SetBackgroundColor(Color.Red);
return view;
}

private TextView GetDrawerView(LayoutParams layoutParameters)
{
var view = new TextView(Context.ApplicationContext);
view.LayoutParameters = layoutParameters;
view.SetBackgroundColor(Color.Purple);
view.SetTextColor(Color.Blue);
view.SetText("just some text", TextView.BufferType.Editable);
return view;
}

protected override void OnElementPropertyChanged(object sender, PropertyChangedEventArgs e)
{
base.OnElementPropertyChanged(sender, e);

switch (e.PropertyName)
{
case nameof(Framework.Controls.SideDrawer.Height):
break;
case nameof(Framework.Controls.SideDrawer.Width):
break;
}
}

public void OnDrawerClosed(View drawerView)
{
Element.IsOpen = false;
System.Diagnostics.Debug.WriteLine("OnDrawerClosed");
}

public void OnDrawerOpened(View drawerView)
{
Element.IsOpen = true;
System.Diagnostics.Debug.WriteLine("OnDrawerOpened");
}

public void OnDrawerSlide(View drawerView, float slideOffset)
{
switch (Element.DrawerPosition)
{
case DrawerPosition.Left:
_contentView.TranslationX = (int) Math.Abs(Element.DrawerLength*slideOffset);
break;
case DrawerPosition.Right:
_contentView.TranslationX = (int) Math.Abs(Element.DrawerLength*slideOffset)*-1;
break;
default:
throw new ArgumentOutOfRangeException();
}

_nativeDrawerLayout.BringChildToFront(_drawerView);
_nativeDrawerLayout.RequestLayout();

((ISideDrawerNativeEventProxy) Element)?.RaiseSlideChanged(slideOffset);
}

public void OnDrawerStateChanged(int newState)
{
// not really needed
// System.Diagnostics.Debug.WriteLine($"OnDrawerStateChanged {newState}");
}
}
}

Any ideas? Support refused to answer this one because it's "code help" (even though there is just no documentation on this).