This got a lot of interest, I'll throw up a diagram shortly, short protection does seem to work, although theoretically it shouldn't, I accidentally tested it while checking voltage at the 510!

How do I deal with the LED indicator? I put it in a light coloured 3mm wall 3d printed box and it just about shines through, but subtly, I've never liked bright LEDs on mods!

I'm using a SUM110N04-2m1P which is one of the 'hardest' to drive MOSFETs around most likely, over 20000pF input capacitance IIRC, which means it needs less than 350mA pulse for a few nanoseconds then under 1mA to keep it 'open'. Used a 9k resistor to speed up the discharge as I don't have a clue as the to switching frequency output of the board.