Re: aluminum boat leaking from rivets
try smearing the gluvit into the gap around the loose rivets first, then while it is wet, tighten up the rivets.
This is how I did all of mine, and it is now very dry inside.
I used to have to bail some water out every hour when I first got it, and now I can spend all day out without a trickle.
The bed liner is still a good idea, not so much from a waterproofing point of view, but to help keep any stray hooks or sinkers out of contact with the hull. From this view, it would almost permantly prevent the two dissimalar metal starting the corrossion thing from happening.