I installed OEM Ford ones on my 19.5" wheels. They will not work over about 90psi. They cause an error. I cold fill mine at 90-95psi all the time and have not had any issues. Got about 10k on them that way. If I had to do it over again I would not install them and just deal with the light on the dash.
I would try putting them in your spare first and see what happens. Some people and their trucks have luck with it, others dont.
You will not have any issues in cold weather. What you have done is very similar to what Chalet does insulation wise (although they vacuum bond). I do a LOT of cold weather camping and I never have a condensation or sweat problem. Last winter I did about 30 nights while skiing, sometimes down to single digit temperatures. The winter before that, same thing. Never an issue.