Finally got it figured out. Thank you so much.
I feel like a moron. I have them both working now, but they spin in opposing directions when connected via the CAN bus connector I made.
Furthermore, forward on my throttle (FSky) transmitter makes the master VESC go in reverse, while the slave goes forward. I have been messing with it (including reversing the throttle switch on on the transmitter, and checking all wiring) and I cannot get the master to behave correctly or get the slave to mimic the master.
What in the hell?
Again, not an expert. But holy cow.