I just went to an adjustable overflow system this year. We were able to seperate the farm use electricity at the place we feed. Running 1 tank heater and keeping the tractors plugged in cost about $120/month. Pumpig water is less expensive than heating and it keeps the water supply to the tank as a nonmanagement issue...
We have a Basalt layer that eliminates being able to run a buried insulated line to the tank with something like a Mirafount waterer....
I have the overflow line running out to the irrigation ditches. It is old well pipe not PVC........So far I have been able to run the overflow to where we don't get water 3 feet past the exit of the overlow pipe. Ok, it has only been two days LOL, but I had visions of a lake out there....
As far as the tractors, we are going to put the heaters pon a timer so it will start heating the block about 20 minutes before we get there reather than continuous....
The first night I set this up, I was told I had to be home by 2 PM for turkey dinner. I went back and the float was not high enough to get water to the overflow. The water was starting to crust over with ice......I had to reach into the tank to adjust the float and it was dang cold......
I checked later and it was pretty good, but the tank was filling closer to the top than I really cared for. So I reached back in to adjust the float. It was surprisingly warm.......
PPRM