Is the blow drying step in the POR15 instructions? I Kremed a tank recently, which basically the same thing as POR, and at the 2nd step, which is to 'dry' the tank, you are not actually meant to make it dry, just mostly free of water. This is done by throwing in ~250cc of MEK sloshing around and dumping out. You should then, quickly, pour the liner in before the metal rusts. I know it looks wet inside the tank after you dump out the MEK, but it's probably something like 70%MEK, 30%H2O. It's not necessary to get all the water out, it should evaporate out with the MEK with is used to thin the liner.
Whether a little bit of flash rust hurts or not, I don't know, but I've read flash rusting is bad too. My tank has only been lined for a couple months now. Time will tell how well it stuck. BTW, I would definitely do a double coat... I noticed a huge difference between one coat and two. With one coat, there are parts of the liner that are so thin that it's almost transparent. With two, it really looks robust.
