I wouldn't worry about it too much. I am in Dallas. We get about as cold as you and for the same period of time. I do just fine. The shaft on my 235 has the weight but no spring. I didn't wire or weld mine open.
If you put Fenton's on the truck they don't have valves on either half. Fred (Joker) has Fenton's on his truck and I don't believe he has problems. Maybe you should trash the exhaust and buy some Fenton's? Smitty's sound nice on Fenton's. Go for it.
