On my old Aspenlite camper, really not worth much any more as it has suffered from some water damage, the entrance door has developed a sag of a quarter inch or so. It's also bent from getting caught in the wind and smashing against the door stop real hard. I think I can block it in frame and straighten it enough to be flat again, but I'm stymied about the out of square thing.

I have not yet recovered from the shock of viewing the price of a new one.

 

I had to fix a banged up RV door once. I took it off the RV and disassembled the framework. Straightened and patched things up and put it back together. A replacement door was in the range of $600.