Nice trukc you got there, but what if those zip-ties snap and your lipo shifts towards pinion. Could cause some fireworks.

Oh, the motor mount is between the LiPos and pinion, so the LiPos can't get near the pinion. The zip ties are a temporary way to hold the LiPos for testing to make sure things worked. I'll figure out some other method later. But there's a physical barrier (motor mount) separating the LiPos and gears.