Thanks guys.
Black Labb, yes, I considered using the mini pots. In fact, I purchased one to get measurements off of. My initial idea was to use a mini pot for volume and two slider pots for the tone controls for each pickup. The mini pot isn't really the problem, the two slider pots side by side are a full inch across. Once I put the top and back plates in there, and enough beef on the top of the bass to reinforce the top and make it look right, it just gets too thick. I could have gone with 3 mini pots instead, and if I ever go back and decide to do a hidden control scheme that's probably what i'll have to do. But doing it that way takes away a lot of the novelty for me, and that was a big part of the attraction of it. Plus, I really like a highly contoured look for this body design, and the hidden controls would really limit me in contouring the back. I may end up turning some redwood burl knobs to make the front controls blend in a bit better with the top of the bass.