I've tried that stuff twice and it frustrated the crap out of me both times.
It doesn't work like it says it works.
It clogs fuel systems and both times it began to desolve in the tank and separate.
Kreem is made for garage queen bikes that get stored empty.
It's way way way too expensive considering it's likely a waste product that some other industry would otherwise have to pay to get rid of.
The correct way is to purge the tank cut out all of the rust and braise in patches with an acetylene torch.
In the case of my fj55 where the tank is a royal pain in the arse to get to, I definitely wouldn't be creating work for myself by using some ultra cheesy and way too expensive coating that's guaranteed to cause more problems than you've got right now.
I'd do it once, do it right, and be done with it forever....