Some years ago in my ice racing (car) days we used to have problems with
side draft weber carbs icing up. We ended up making a loop around each carb
with heater hoses then on into the interior heater. It looked a bit weird
but worked really well and we never had a problem again. Your tractor
probably doesn't have heater hoses but I'm sure you could "T" off the rad
hoses and accomplish the same thing. I apologize if this is too far off
topic.
Colin