JUR is a good idea. I'll look into getting one locally.
Some progress today... I finished up the woodwork part of the build, and sprayed on a coat of black tinted polyester resin over the whole tank:
The pic with the wood covering the tank is just to keep the heat in... I set up a 5kw electric heater blowing into the tank to make the resin cure.
I also did the fiberglassing of one seam this evening... unfortunately I don't have any mat left, I thought there was more in my stash, so I'll need to get more before I can continue.
Small update this aft. I know I'll regret doing this, but I'm a bit anal and I like the things I build to be finished from all angles.... even if the angle is up against the wall. So, I spread a coat of resin with bulking filler across the outside of the back panel of the tank to fill in the crappy texture on the exterior plywood. This means I have a lot of square feet to blocksand now . I did this on my last tank build though and I'm glad I did. i don't have to worry about water damage or mold on the back of the tank due to splashing. or condensation or whatever. I won't be filling and sanding the tank bottom, but I will spray it with polyester as well, because if moisture is going to creep anywhere and stay hidden, it'll be under the tank.