AluminumAlloyBoats.com

What is the best practice for canvas enclosure / cover snaps on alumiunum hulls?

I haven't been able to source aluminum snaps, looks like SS or zinc are the two common options.

What is the best way to attach to prevent corrosion, both on painted and unpainted surfaces?

I would say a liberal coating of Tef-gel on the SS and you should be okay, I have SS bolts threaded in my gunnels for my rod holders that have been fine for 10 years.

Had a cover for my old ski boat. No snaps, twist locks or any other fasteners.
The cover would lay over the boat with a pole near the center and had a cinch line like a hoody that pulled tight below the rub rail.
Worked great setting still through a few hurricanes. Never tried trailering with it on.