Yeah, this is actually not bad as you're going to expand it. As for that second 84 hp skiff, I'd actually suggest using that plus a nice clocking/trigger sequencer for the drum modules. It'd give you more room in what would be the 'main' cab, and turn the skiff into something 'mission-specific', namely a bespoke drum machine. If using the BSP is the idea, then I'd say load that skiff up with drums and some mixing (stereo, natch) plus a little bit of FX to make a beefy little drum box when the BSP's in use as the controller. (looking at one of my BSPs) Hm...yeah, this is really a doable idea. Here's what I'd do:
This is probably totally irresponsible as far as drum skiff designs go. Much of it is 808/909, but there's some weird crap added, such as the screwy dual tom module and all the crap on the left side, which allows you to build two more drum 'voices', one using external signals and the other with chipnoise racket, and both gated by a dual AR controlling a dual LPG. Two mixers down on the end allow direct-output in stereo, with four pannable voices and the rest in some variation on mono/center. I have a distinct feeling that this might be capable of hurting people.