Then use more screws. Stud them all the way down the perimeter of the back 1cm apart for all I care. Still better than heat-guns and prying.
Cheap aluminum boats are still riveted, welding preferred for obvious reasons. I have an old riveted aluminum John boat and is leaks through the rivets and seams...
> Cheap aluminum boats are still riveted
I think you may need to think out your entire post before typing such contradictions.
Riveted hulls worked for hundreds of years and well maintained they can last forever. Just bacause welding makes it cheaper to maintain in the long run does not detract from the fact that riveted hulls are very performant, which is why they were used everywhere that needed not only waterproofing but pressure containment too.
Ship vs boat is also not a contradiction.
Ships != Boats