The pic from the rear its obvious the rear axle camber bow is the wrong way for what ever reasons.
I would contact the rv dealer and see how quick they can replace that axle. Or check with area big rig trailers repair shops and let them have a look at it. They can rebend the axle tubes back into proper wheel alignment specs or replace the axle assy for you.
Its harder than some are saying And yes I've change several on the road or at the truck yard. You tube vids can give you a idea of the equipment involved and tools needed.
