I like the drop zone concept and the fold-down desk.
I put plus nuts in almost every available hole before attaching furring and paneling, then L-track where they lined up. When hauling, I'll use the track to secure cargo. When traveling, I'll use it to mount furnishings such as a fold-down bed & desk on the driver side, modular galley on the passenger side, similar to your plan. Eventually. For now, I'll just chuck in a cot, folding table, camp chair, camp stove and box of camp cookware.