Maybe just a dimple in the stay?
sent from a banana phone...
Interesting way to mount a bottom bracket!
Custom builds with derailleurs usually have chainline issues, maybe hang a derailleur sprocket as a jockey wheel off the back of that tube the bottom bracket is on? That would lift the chain up and should give you clearance...
Well that's different! I like the concept, hope it works.
Now take the next step and have both derailleurs articulate in concert with each other!