A hitherto untested medusian PWM board sent off to OSHPark. For servo power, one can connect a JST PH connector, 3.5mm terminal block, or vanilla 100mil header. An on-board LDO powers the PWM IC from the bus power connection or the 100mil header breakout. Its enable pin is routed out to the bridge connector (PA02). Current configuration does not support an external oscillator. I2C lines are broken out at the same location as on the controller board (I2C is part of the bridge connection). Solderable 0603 jumpers exist on the back side for I2C address configuration. Presumably can dissipate 400mW :)
I laid this out rather quickly so I might make some changes after experimenting with the first cut.