Do you need to control the temperature remotely, or just switch it on? If the latter, could you just leave the existing potentiometer / power switch always in the on position and add a new zigbee relay to cut power to the whole works on & off?

Six years is recent enough for decent virtualization support at the CPU level, so it’ll probably run within 5 to 10% of the “native” performance you could get with Boot Camp. If you have enough RAM to give the VM a decent amount it should be fine.