Early on there was some talk about a clear coat that Tremclad offered in Canada. I was diappointed to learn that nothing was offered in the US by Rustoleum.

I may have found a substitute:
http://everbrite.net/coating_properties.html

Anyone ever heard of this stuff? I called and they said that it can be applied over new paint like Rustoleum after 30 days of drying. This looks like it may have great potential for enhancing the final results of the roll-on paint method. Says it's self leveling too.