Dreamer
I've had mine in the humidity of Ohio at the Fling, and 110F temps here in Fresno during the summer, and now I'm driving it on 30F misty days....
No additional insulation and no heater. The footbox air vent on the driver's side does a great job in the summer of moving some air around. During the winter days, I close it and stay pretty damn toasty with a good jacket. I've kept that firewall panel closed as well.
Why not give it a try first? I think you'll find it does just fine with the range of temps you expect.
Have a great build and enjoy it...ya got a good one.
