I'll second that. You may even want to seal the edges with glue a couple of times to make sure all the pores are completely sealed before painting. It will extend the life of the plywood many times over. That's the weak spot.I would suggest that you seal the edges of the plywood with TiteBond II or III before painting.
I don't know why you have to take on that sort of attitude. Just like everything else in beekeeping there are many ways to do the same thing and many opinions. None of which are put out there to prove you wrong or mislead anyone into trouble.If it is important to prove me wrong, by all means lead the newbees into trouble. I am wrong a lot but not about this.