I saw your other post after answering this one. I am still not sure what you are trying to do, besides having 4 6V batteries for dry camping. You can't put them on the tongue, and you have no ready-made place to put them.
Some suggestions and hints based on my experiences:
- as was stated in the other thread, normal wet cell lead acid batteries must be in a space ventilated to the outside, not to living quarters.
- are you looking to permanently install and wire these batteries? Paralleling battery banks requires fairly equal batteries to avoid emptying charge into each other (don't ask me how I learned this). You will not be able to easily parallel the group 24 12V with either 6V bank. You will need bank selection switches for a permanent install.
- a temporary hook-up to a battery bank with battery boxes on the ground is feasible. But where/how to transport still remains an issue.
- how long are you dry camping for? What are your loads? With some effort at conservation, two golf cart batteries (220 - 250AH depending on batteries) can give you 4 nights of camping without going below 50%. They can do longer if you are not using the heater.
- if you need all that capacity (440+ AH), what about solar or a generator to help your batteries out?
2014 Rockwood A122 A-frame
2008 Hyundai Entourage minivan
using an Equalizer 2 point WDH/anti-sway took away the issue with tongue weight for 2nd battery