Just like the heat tape the radiant heat panel will need to be controlled by a thermostat. The thermostat will keep the RHP at the proper temperature year round.
You can always add a RHP later if you need one. Installing a RHP is very easy, all you have to do is drill a small hole in the back of the cage for the power cord to pass through, and then screw the panel to the ceiling of the cage.
To start out with I would get a T8 with heat tape and 2x fluorescent light fixtures. These will add some heat to the cage. Have them on 12 hours a day. You will need a good thermostat to control the heat tape. I would recommend the herpstat 1. Later on you can get a RHP and a second herpstat 1 if needed.
If you want to just get everything setup from the start then instead of getting 2 herpstat 1's you can get a single herpstat 2. A herpstat 2 has two separate thermostats in one unit.