@7f73a7d1 the upper MOSFETs would be driven by a CMOS gate so the resistor probably wouldn't do anything (it's low impedance 0V or 5V, never high-Z).

-5V Vgs on the upper MOSFETs is the bit I missed. I'm now trying to work out if that's actually a problem in practice. they switch on and off in the order of 120Hz at most, and are only handling tens of mA each. the Vgs range is spec'd for ±12V so seems ok? 

 @f3ad697a Yeah, if it's within the datasheet's specs, it should be fine. 5V isn't much. I just wasn't sure if you actually meant 5V or if that was only a mockup for the simulation's sake.