Here is the steak saver. It lets you connect the 1 pound propane to your camper.
This 5 pound propane bottle drops 16 pounds, but still allows you to run you water heater and fridge off of gas. It would easily get yo through a week long trip.
Doing some searching, a group 24 battery weights about 41 pounds. A small motorcycle battery weighs 5.
36 pounds for the battery + 16 for 5 pound propane bottle = 52 pounds reduction in tongue weight.
It MIGHT even be possible (extreme) to use a 12v drill battery to use in place of the motorcycle battery. I'm not sure if that would meet the power requirements for the emergancy brakes.
...she started talking about how I never listened to her or somethin, I donno, I wasn't really paying attention...