The marinco cockpit electrical outlets are factory installed. It is the outlet most USA customers use with their kite reels. Rather than re-do the plugs on the boat, most people just re-do the plugs on the scotty's from Scotty to the Marinco plug.
For the prawn puller solution, if your wire gauge is not sufficient and you want to pull traps immediately you could just get a 12V portable battery with alligator clips and power the puller (provided you're not pulling a dozen traps in a row or something heavy duty).
You may also find if you the generator and battery charger and the same time you might not pop your fuses. If you think that as you load down your 12V system with draw from the puller (and everything else on the 12V circuit) the current draw will go up to compensate for the voltage drop.
Something to consider trying; try running your generator and battery charger, and/or run your main power engines in neutral at 1500rpm or so while pulling traps to inject power from the battery charger or alternators. If the puller draws 35A at 12V, if you can get that voltage to 13.5V your current draw would only be 31A. If you sag the voltage down to 11.6V your current draw would be 36.2A.