Another solution, a toolbox I reclaimed to mount on the tongue:

I painted it black and the inside now looks like this:

I decided, after I mounted the box, to not use it for batteries and installed 2 6V GC2's inside the trailer in a vented box. I did it mainly for weight distribution but ended up with shorter runs to the DC system area, also.
After I finished both of the boxes, Torklift sent me a dual 6v box for evaluation, go figure. I'll probably mount that on the back and use it for gear, now, and possible future expansion later. I wouldn't have dreamed when I started with this 22' TT, I would be looking at possibly having 9 batteries, lol.