What about Pico DSP ? I could also use a smaller out instead of the Ooots and shave some HP.
I own both and the algorithms on the FX Aid are waaaaay better than the ones on the Pico DSP. I think you should use the Zoia and save some HPs.
I also have an Ooots and while I really like it as an output module you could definitely use that extra space better,
I read some posts somewhere talking about how difficult it was to work with some of the more smaller versions of Plaits so thought I would make an exception and just use regular Plaits. I'd be interested to hear others experiences with the other compact Plaits clones...
I own a 8 HPs one and the ergonomics are not that bad but YMMV.
As far as Clouds go, I really wanted the Microcell (Im assuming you know it has three different Clouds firmwares which kinda makes an amazing module)
Switching firmware on Clouds is easy enough, and, again, you may definitely benefit from squeezing some more functionality in that space.
That said, I agree with everyone else in saying that you will be very limited with this setup. If you really (really) want to do this within the 42 HPs limit I'd recommend you to at least get a Marbles instead of the Turing Machine.