That's a great battery layout you have and the cabling is A+.
I had to deal with the wheel wells on mine. It looks like you have a flat floor. That would be nice, but your trailer is a lot higher than mine too, but since you go off road with it, your setup is perfect. I stay on the paved roads and like to have at least electric hookup. (I'm spoiled)

The D hooks were for the dinette table. In it's original config, you could drop it down to make a bunk. We never used it for that and it was too cramped to use as a dinette, so it went away! I mounted the benches to the floor, so it don't move. :) I can put it all back again to original, but I'd have to fix the new cutout the bench now has to clear the wheel well!
Mitch