I'm thinking along the same lines, although I don't want anything larger than 8x10" (the 9.5x12" camera I have already is perfect, the 12x16" is too large for me).
I'd definitely go for the largest possible lens board. My plan is to get two or three boards, and put an iris mount on one of them for the lighter lenses, and do a "proper job" with the big heavy beasts. Like the 500mm f:6.3 Krauss/Zeiss Tessar, if I decide to get a long enough bellows to use it.