It's almost 60 today and lots of bright sunshine. I'm going to chance it and try to get a coat of etching primer on. Then, I'll let the tank rest, maybe put it somewhere it can stay warm for a few days before I put the filler coat on. It's supposed to be 70 here Friday. I'll post results.
Pilot error? Most probably
I'm just glad I didn't have to report it to the FAA.