Something to consider--
I've been a proponent of using building foam to support the TC but have learned a bit recently that you may want to consider depending on your TC construction.
My Palomino TC had no basement and the tanks were elevated above the bottom. It had 3 external metal floor supports running across underneath the floor. This construction worked great using the building foam to raise it. The only areas where the foam got compressed was where the metal floor supports were.
On my AF the weight of the TC is supported by the perimeter walls of the floor tub. There are light duty frames from side to side, covered with an 1/8" bottom, that support the tanks but are not strong enough to support the weight of the camper.
The problem is, during movement the foam compresses some around the edges which puts excess pressure on the cross frame.
All my tank supports were cracked, leaving me thinking this could have been part of the cause (not all), and I will no longer use this method of raising the TC height.
It needs a solid support on the edges. Other camper such as my Palomino work great with the foam.
The radius of the tailgate opening doesn't interfere with my TC, as that area is still wider than the wheel well width.