hold on there regarding using a tank sealer!

Why would you want to do anything different than the instructions on the tank? There's a sticker on each tank and threads here on how to slosh the tanks to clean them. Not to be dramatic but pilots have been killed with fuel issues. Please don't try some motorcycle slosh just because it works on a bike.

Even if you are going to put the sealer on the outside I'd stop and search threads here.