Safariel,
You need a "Big Daddy" rivet gun($150) and a small but fat stainless becket with a 3/16" hole, that fits down in the tract.I salvaged mine from an old block.You may have to remove the entire tract so you can use those rivet casing beneath the tract to accommodate that over sizes hole from the pulled out old rivets.If you buy that gun than your buddies can borrow it

.I think those rivets are countersunk so order them from Hobie and use the right rivets.Hobie is the only source for the rivet casings that I have found.
Good luck, Bill 404 21SE