Andrew,
I've had pressure treated wood contacting the ribs of my aluminum boat since 2002 and no issues, but, it's the old arsenic based pressure treated, not the AC2 type. I've been told the AC2 is more corrosive to Aluminum. With that being said, I would think you would be able to "insulate" with rubber or thin foam so you're not in direct contact. I've also used Stainless screws to attach it.
George