The racks do not need to be run independantly. There are 2 temp sensors on the Herpstat 2 and that is what it is meant to be used for. Plug the racks directly into the Herpstat 2 and then plug the Herpstat 2 into a nice surge protector. Ensure you are monitoring the proper sensor on the proper output control of the Herpstat 2.

I'd get a Herpstat 1 for the incubator.