Michael is this a question is your post a question???
I'm finishing up my fifth canoe using Kerby's paint. As you've no doubt found out it has the consistency of syrup. I always use penetrol as an additive to help it flow more easily. I know their instructions say you shouldn't use a paint thinner although for a first coat I have used a small amount. I do however find the penetrol makes a difference so use it with each coat.
I've found if I could find a 4" roller that doesn't have lint (can wrap a new one with tape prior to using and then remove to get rid of lint) I then complete with a stiff (NOT HOME DEPOT) foam brush I end up with a nice smooth finish. Haven't tried a foam roller but that might work unless you're pushing a lot of paint ahead of the roller.
I've just finished 4 coats on my current project but plan to apply one more anyway this time. Last one is either going to be with a new brush or the foam type. I've been wet sanding with 220 between each coat.
I love the Kirbys Bottle Green and used penetrol - but not enough. You can call and talk it over with the great people at Kirbys and they can give you some guidance. It definitely needs to be thinned.