I have the same situation on my tt.
My plan is to add a truck, side mount toolbox on the tounge, parallel to the front wall of the trailer.
I can get as much as 6 feet of storage room in width.
I just have to be careful about the interior dimensions of the box.
I plan to section it off with plywood or similar.
I can put two batteries to the curb side, then a plywood divider and have storage for my chocks, levelers etc, in the other half, and my batteries are in a lockable compartment.
I can install a battery switch inside or out.
I'll drill a couple holes for venting gasses to the outside, possibly through the bottom.
When I get to the project, I'll post pics.
I'll keep watching this thread. Someone may come up with a better idea I hadn't even though of.