Why not just make a Midi to CV adapter for the Sub 37? Why waste the R&D on this when you could put it towards doing a Polyphonic synth?
If I recall correctly*, the Sub37's architecture isn't friendly to a native CV out kit as was the Little Phatty. If you're stuck with MIDI-to-CV, you're better off using something like Yarns to interface with eurorack.
As for the Moog Poly... Jeep is finally making a Wrangler Pickup, so I guess anything is possible.
* I don't feel like looking it up, but I read something by Amos or someone somewhere.