A friend of mine had a very leakey jon boat. What we did was use the heavwy duty rivet gun ( The type that is used to maje sheet metat repair on buses. When we got that done(one days work) we to the boat to Line X and the inside of the boat sprayed with bed liner coating.He was able to use color of choice(Red).
The boat looks great abd never will leak. All was done for less that $500.
Hope this helps