I have to get a little construction job finished on My house first. A cantilevered closet. Then I'm going to start my "cat" hulls. I'm using a two part epoxy made for aluminum with an hour workable window. I'll have the holes all drilled to keep the joint clean. To prep the "AL" I'll sand them with 120 paper and clean it with Acetone and rinse with distilled water as per instruction . I have an air hammer and set and a buck. Any tricks ? How many rivets ? Ext ?