Couple of thoughts:

Make sure the door catches properly and well. On our new 2001 2720SL it didn't and had to be worked on.

See if you can get a hose and spray all over the camper, around windows, along any edges. Ours had a minor leak and had to be recaulked around a window.

Maybe the dealer could fire up the furnace to get propane in the system and then check all over the gas lines and tanks for leaks.

Maybe you could put water in the tank, turn on the pump to pressurize the system, and check all over for leaks.

If you have one, make sure the hanging cabinet is level. Ours wasn't.

Have fun!!!!!

Phil