You want to run each heating source on its own probe and thermostat, I have flexwatt and RHP in most of my cages, the heat tape is only going to create a hot spot, not raise ambient. So if your room temps are warm enough you can run only the heat tape. If you need the entire tank heated the RHP will do that. Both are extremely safe methods of heating as long as they are controlled by a thermostat and are fine to be used together or separately. The probe isn't going to make your cage wobbly, you can't even notice but I would have it raised off the ground personally.