Which batteries will work?

Theres always the Honda 2200 generator option. We boondock too. Lots of my friends setup the small honda instead of running their larger onboard genny. Over time the gasoline saving must be huge.

you need two agm batteries for boon docking. lot of power , deka is one good brand. or you can go wal mart deep cycle marine on the cheap side. remember this ,theres only three battery makers in the U.S they just slap different names on them and change the prices.

If you have an extra inch or two above your batteries then the hands down way to go is the Costco or Sams Club dual 6 volt batteries. They are basically the same price as 12v automotive batteries and have a lot more amps on reserve for when the generator is off.

"I now have to run the generator every night for medical equipment. All we ever do is boondock/dry camping"

With adequate batteries and solar charging you would rarely need to run your genator. Start with an energy survey to determine how many AHs you use, multiply by 1.5 or 2.0, buy batteries with at least double that amount, get solar panel watts at least equal to the total AHs of the batteries....and go from there!

I would do anything to bring generator usage down to a minimum, including solar, inverter, more battery and charging during the day. But, since I see you're in a TC, that may be difficult.

I don't think anyone on here is going to recommend car batteries.