Thanks for the feedback guys:
Regarding the angle grinder sparks, honestly I was just using it for the picture. I used a sawzall for a couple of hours then tried the angle grinder. The sparks were impressive so I snapped a picture, then went back to the sawzall. If you look, you can see I'm actually just buzzing the surface. I'll check out that Bosch tool though. Getting the bottom of the tank off looks nearly impossible with a sawzall because the hull
is maybe 1/2" away from the tank.
Regarding a temporary tank, that's what I'm doing. Found a little 22 gallon that I can strap into the engine
compartment for $200 and it will be here by Monday. With the rate I burn fuel
that's roughly 40 hours of motoring so should be sufficient with some deck
cans to boot. I dig the idea of a drum, but stowage space is pretty limited on this family
loaded cruiser already.
Regarding the leak, it was from the bottom somewhere. When it was completely open I filled it with water
and dish soap maybe half way, definitely 6" under any tank fitting. The drip came back.
I taped some plastic trash bags over the tank to shut the smell down (can't fully clean it out as much as I like).
Whew... should be enough to get to Mexico