For minor pitting, I would sand as best you can, use an acid-etch wash, zinc chromate primer (2-part from Petit), then 2 coats of Easypoxy (1-part from Petit). Brush it on. All available at Fisherman's, GI Joes or W. Marine.
Gluv-it is hell when it starts to crack, which it will. It also doesn't do anything structurally to the point where you can rely on it. If your pitting is really bad, you need new aluminum.
Also, why are you getting pitting in the first place? Is your electrical system grounded to the hull? On an aluminum boat, it shouldn't be. Check for disimilar metals. The only thing in contact with aluminum should be paint, other aluminum, wood, vinyl, plastic or other inert items. Stainless will make aluminum oxide but it's hard to avoid fasters of some time of metal. No copper, bronze or carbon steel.
Biederboat