im using the same polyester that every guitar company, except gibson, uses.....
your schedule has a lot of sanding and a lot of coats and a lot of sanding between coats.....you may want to upgrade your gun, you should be able to lay down urethane and epoxy primer(which is also the sealent) without any sanding...allthough a lot of people scuff sand reall quick with 1000 grit, but you really dont need to as long as you keep going
with polyester, the schedule is polyester sanding sealer, sand to 400, paint, clear(which is done in sages every 15 minutes, starting with a tack coat and ending with a 4 th or 5th flow coat)...it flows out pretty smooth...then wetsand and buff.....it produces an indestructable clear coat thats resistant to scratches
polyester cures anywhere from a few hours to a day depending on temp.....pot life is about 40 minutes....the best thing about polyester is you dont have to worry about anything, no fisheyes, craters, peel, fogging whatever...it pretty much bonds with everything...but you do have to have the right equipment and know how to use it....and there will be a learning process at first where it seems impossible