I also work in the basement which gets pretty humid. Lately its been pretty tough trying to paint anything. I did a little experiment the other day though. My friend is a body guy and he told me to keep the booth warm when painting. So....I have a small fan type heater, I turned it on in the direction of my paint booth and let it warm up the area for a few minutes and it actually brought down the humidity about 10% which put me into a safer painting climate. At this point I turn on the fan to pull out the fumes but keep the heater pointing at the booth. I cleared a few parts and a body and luckily no fogging and everything came out very good.
If you can take the heat, its not that bad.
My next thing is to get a dehumidifier, but they are pretty expensive so I dont know if its worth the expense.