[RidgeRunner]

Yep, That is a hot coat. With Vinylester it helps to penetrate into the wood and gives it some bite. Essential on Kiln Dried PT Plywood IMO. With PT plywood the cells of the plywood that would ordinarily be open for penetration are actually full of preservative, metals like chromium copper and arsenic. It can give a case hardened effect making penetration difficult, that is why I recommended you grind it with some 40/60 grit before laminating with glass.(It helps the mechanical bond) Always wear Personal Protective Equipment when working with PT or any time you grind or sand on glass.
If you seal any type of plywood properly it will work for a long long time. I do not consider Wellcraft's glasswork to be that outstanding. My hull had lots of voids and buggers once the foam was removed.
ACX Fir seems to be a lower cost alternative to Marine Plywood and is available at most of the Box Stores. You need dry and without contaminants.

I have always mixed the hardener in with the resin. I'm like Spare, how does the resin underneath harden. I try to keep the ratios of hardener to resin consistent at the low end of the scale so I can have the most potlife and work on larger areas. (Mind you I glass in 95 degree weather) I threw out more kicked up in the bucket resin than I care to admit trying to find balance.