What about a clamp on system over your battery on the tongue? Mount a bar up and over the battery/propane tanks. Might add a bit of tongue weight, but if you have room to add some, shouldn't be a big amount.
Now if it is a 5'er (or even a TT i guess), maybe a roof rack on the RV? I have seen people put kayaks on their rooves. you would probably want to design it so they lay as flat to the roof as possible, though, or you might have some fun underpasses. lol
Just some brainstorming. May or may not be feasible, but you gotta think outside the box to come around to a good solution sometimes.