OnSizeAllocated, UseSafeArea, changing layouts by orientation on iPhone X

We use OnSizeAllocated to drastically change our layouts between landscape and portrait modes. Having to do an update, which means I finally have to deal with the iPhone X issue. I've found a problem that I'm not sure how to work around.

Setting the page to UseSafeArea is all fine and good until OnSizeAllocated fires. Seems the width and height for OnSizeAllocated don't take into account the padding placed by UseSafeArea. Likely by design, but it means we don't have a simple way to determine the actual usable width within OnSizeAllocated. I've looked and don't see an easy way to just say if this is an iPhone X reduce the width and height by the padding amount (don't want to do it for all iOS11 phones)

Any ideas on how to deal with this? I've searched for a couple hours and been unsuccessful.

Thanks!