Harbor Freight sells a portable welder for a hundred bucks.
It is very small and fits in my front hatch.
I never leave the shore without the welder. Mig, arc, whatever, I can weld any metal parts on the water.
Another overlooked item is a water desalination system, mine runs on 12 volts and puts out 50 gpm. You need fresh water to rinse the welder parts with.
Seriously, don't over complicate your day with too much stuff.