It's just a cool-running tractor. You can run them without thermostats as mentioned, but I did order one for one of my B's - it was a 150 degree thermostat. The tractor runs 150 to 160, maaaybe 170 on a 95+ degree day. I haven't seen it it 180 at all. My CA is the same way, and I've cultivated with that tractor in 100 degree weather for 10-12 hour days when I was younger.
I think the thermostat is a good idea - get the temp up to try and get at least some of the condensate out of the crankcase. If you don't have that regular oil changes are a must.
And by the way, if the fan stops turning it will overheat in about 3 minutes or less - had that happen when I installed too long a bolt in the cowling by accident - which hit a fan blade and stopped it from turning (had an althernator and a small belt on it at the time and was easy to stop the fan).