"Room temperature" in my garage is around 65 degrees lately. My house is pretty well insulated, thankfully! Actually, I believe the "frosting" or "fogging" effect from the Valspar (which I've heard is a common issue) was due to too much humidity, of all ridiculous things. The joys of living in Georgia.
However, I ended up using the Testors Dullcote, and it worked perfectly. Photos will be incoming as soon as I finish up the ears, but I'm incredibly happy with the finish now.