<So, is this what an air-cooled is like in winter?>

If you've lost all feeling in your feet and can't uncurl your fingers from the steering wheel then...YES!
I drove a swiss cheese  '62 Splittie (full of holes and NO seals) from Natural Bridge to N. Virginia last Saturday-almost made it, broke down on I-66 about 25 miles from the destination. Had to wait about 45 min. for tow truck, then tow truck driver had to stop to change a flat for someone then had to stop for fuel. He apologized for the delay, I laughed and said not to worry, at least his tow truck had heat!    Jeff