What should I use for a floor on an 18' 1976 starcraft aluminum hull. It has cedar stringers wrapped with thin aluminum channel. I heard pressure treated is a no no on aluminum. I want rain to go through the floor and out the hole in the back of the boat when it sits in the yard. This way air circulates under the floor preventing any rot. How tight should I get the floor to the walls? Should I connect the floor to the walls? If so, how? I figured on leaving a space between the walls and the floor, but I don't want to loose stuff like keys and lures in the gap. I also don't want to put in carpet.