I would probably move your PROPANE TANKS to the front of the trailer tongue and add one of these 48-inch side mount diamond plate tool boxes across the trailer tongue between the propane tanks and the trailer front wall.
This will allow you to add up to four each GC2 6VDC Batteries (two groups of 6VDC Batteries in series) to give you around 450AHs 12VDC Battey Bank capacity.

It would look something like this when completed...

Search GOOGLE for 'gilldawg79 battery bank' and when it loads up select 'IMAGES' for photos of this mod...
This is a layout of my switchable four each 12VDC GP24 Interstate battery setup.

Looks like this across my trailer tongue... I originally had four each 12VDC batteries here but lost one due to boiling out the battery fluids. My next layout will be using the 48-inch side mount tool box...

Roy Ken