You can get better FETs these days than 0.020R, you might have to use a non logic level one though and you will therefore need a driver
Agreed. I've already found several logic level FETs with Rds(on) in the 5 mOhm range but haven't tried them out yet. I currently have a fan blowing on the heatsink that is keeping it tolerable. The FET I'm using has built-in overcurrent, overtemp, etc protection but that may be overkill for my application.
You need more bulk decoupling on the power supply. How much have you got now?
Good question - thanks for the tip. I'm probably applying bigger transients than the designers planned on. Lifting the cover on the supply, it looks like a pair of 1000 uF caps.
Hope the OP is finding all this helpful