Hello,
I have a 2001 S and S 9.5 non slide 4 season camper with two 20lb propane tanks onboard and an Onan 4k lp generator. We have camped in 90 plus temps and as far down as 15 degrees. The lp is used for our fridge, cooking and heating and cooling. We normally have the AC at 75 and the heat at 60 degrees. Very comfortable for us! We can sustain our camping experience for almost two weeks!
If we simply boondock for a cold weekend (mid Friday to late Sunday), we use about a quarter of our 20lb tank.
We are very happy with our generator at this point. It runs like a charm.
Of course any use will depend on size of camper and personal comfort.
Good luck with whatever you decide on!