I will second the "Warbird Colors" good experience. It isn't Latex, but it is water based and it is fuel proof. I've sprayed latex before and I have to say I prefer the WarbirdColors paint application process. It is a polyurethane of sorts and sprays like an acrylic, working best with HVLP guns.

I just glassed and painted a P-60 powered jet with it. It dries hard and can be masked and worked with in an hour or two. From what I can tell, it isn't much if any heavier than any other paint except possibly a lacquer based paint - those are nearly impossible to beat for lightness. But I can almost guarantee it's a lot lighter than other epoxy based paints.

I would agree that latex could possibly be tricky with paint seams. Not so much so with the Warbird colors, relatively speaking. If you are repairing an area it is best done by masking off a "panel" area and then sanding with 1500 and 2000 grit, and clear coating over the seam area. I've already done this when fixing a couple mistake areas and it's worked. Be sure to prime under the paint, it needs something to stick to. High quality, relatively light weight lacquer primer bought from an auto paint shop (in a can) under the paint works like a champ.