If you are regulating the snakes currently just move one of the regulators (rheostat?) to the rack and use that same method you are doing now. Remember racks really do best in regulated room temps if the room is stable a rheostat will work fine and not need massive adjustments. An on off will also work with indirect heat and a proportional will work too. I would suggest that a proportional unit is better but regulation can come in a lot of guises. I would always suggest that a back up system is wise failure can occur with any regulators.