There are closed end pop rivets at harbor freight and a few other places which worked very well on a 20' jon boat that I reworked last summer.
Got the idea from this site http://www.traxstech.com/Boat_Repair_Rivets.html the HF route was mucho cheaper and IMO just as effective

Drilled the original rivet out with a 3/16 bit, resized the hole 1/4" bit, Squirted a bit of 3M 08300 seam sealer in the hole and on the rivet. Popped the rivet and let the repair set overnight. Replaced 44 rivets. Next day. installed the bilge plug and filled boat with water, no hull leaks after 8 hours, except the bilge plug was not fully sealing and had a drip there. All work was done from outside of the boat.