I haven’t tried mixing brownout plus eeprom yet, but I may have to do a quick mod to see if it ends up using less space. 
Go for it! I think people would be very interested to see your code, especially because you’re using different MCUs and different pin layouts. We could use some fresh ideas around here.
Since it’s not really STAR any more, it might be good to switch over to a different thread to avoid cluttering this one any more. I know I’ve dumped too much off-topic stuff in other threads, so I made a new thread for firmware in general:
I would imagine we could also use a thread for info on your driver hardware, if you’re willing to write up the details. I liked the M6 “BMF” thread, and would love to read more about your other work.