Thats why I mentioned the "crane". Those need 3 points to mount to in the rear of a vehicle and they can be had for sedans of all shapes and sizes. Then the mobility device that is lifted can be disassembled while the trunk is opened and folded up likewise for the crane assembly.
I saw a prius v the other day and the rear looked similar to a riced out highlander with clear or chrome tail lights. Other than those horrible tail lights it "looked" roomie.
Having said that Ive tried a few vehicles with sliding rear seats and its an either or. You get room for rear passengers or room for rear cargo, but not both.
Granted Im a foot taller and 100 lbs heavier than anyone in my family I could put my mother and father in my insight. Then a walker in the trunk and folded up the 40% seat behind the driver and placed a second walker or my fathers wheelchair there.