Another thing to remember with poly sealer is that it doesn't work with all stains, and most of the time I use a barrier coat over the stain before the sealer. Binks makes a plural component 2 quart pressure pot system. You will need to experiment with the catalyst ratio when using plural component systems, as the catalyst only gets mixed on the surface and you need more. I used this system and was quite pleased with the results. Plus, there is no pot life issue.
Polyester is one of the most amenable finishes to spray on.
It also solves the problem of mixing up finish, so you can spray on your tack coat and leave the finish to set before your flow coats and before the finish turns to rock. If you thin with acetone, it flows out very well. For large scale, mostly polyester primer, I use a Binks Gemini pump and a Mack 1, and as long as you keep new mix in the feel can, you do not have to worry about it hardening in 10 minutes. If you are going to spray all day long, then spend the money for the plural system. I aren't on speaking terms.