Aircraft dont use pop rivets in structural applications, you cant guarantee how much load they will take before they fail for various reasons. Aircraft mostly use solid aluminium rivets or Cherrys http://www.textronfasteningsystems.com/aerospace/html/product/rivets.htm
Araldite make some of the structural adhesives I use in addition to rivets on aircraft, they have good range for marine as well.
Personally I like a reinforced box section beam, due to ease of fastening and simple load paths.
Darryn
Mosquito 1704