In need of advice/ answers for my boat project, 1st timer

This is my first project, my boat is a 1648 alumacraft. It will be a hunting/fishing boat.
I want to remove the middle bench to allow for more, being new to this I'm not sure how to properly "rework" the new rivets to ensure no leaks. I also am looking for advice on any "paintable" coating I can apply to the bottom of the boat.
Thanks, Jim!

If you don't want to deal with the rivets just cut the middle third or half of the bench and use the remaining pieces on the sides as seats or storage compartments. There are plenty of examples of people doing that on the forum. If I find one of the threads I'll post it for you.

Steelflex is a good option for the bottom of your boat. It is a little painful to apply but it was worth it in my case. You can see it in my build and many others on this site. You also will not have to worry about leaks if you use it.

Just noticed you wanted something "paintable" though, so steelflex may not be what you are looking for. I did another boat that I just used steelflex on the bottom and about 3" up the sides, then painted the top portion. That may be an option for you.

IIRC Steel flex can be tinted.

GatorGlide is awesome too, it comes in several colors.