Seems like you have done your research and you are definitely on the right track. With something this small, you will probably want to pack as much functionality as possible into the small space without sacrificing playability and fun. There's a trade-off between tiny modules and the fun factor, so a balance of large and small will maximize functionality and ergonomics. You also will probably want to consider a few function-dense menu-driven modules that detract from the one knob one function approach, but give you lots of options.
Maths and Disting are almost "must haves" in your case, from my perspective anyway. You can do the subharmonicon patch with Maths and DFAM (see Loopop's video). Disting does a bit of everything, though only one at a time, so you can add oscillators, filters, effects, waveshaping, utilities, etc. depending on your needs. You have attenuverters included in Maths too.
Veils and Kinks are probably the route I would go for VCAs, logic, and S&H. Pons Asinorum is a cool multi-envelope generator/LFO in a small package. Pam's New Workout can do all kinds of neat clocked things.
Take a look at how I might approach your specific build below. I'm sure others may chime in with other ideas.
Have fun and good luck.
*Edit - Keep your mults outside of the case with those inexpensive little star-shaped external mults you can find at most modular retailers. You probably won't need a buffered mult at this point.