After starting with lights like that myself for the same reason as you, and after gradually expanding my collection, I ultimately just started using a room heater plugged into a Johnson Controls thermostat.
I can understand using a light for just one animal. I initially had thought that you wanted something for constant temperature control of the enclosure.
Being a cheapskate, I had inner turmoil about buying an electric oil heater and using extra electricity all winter. I keep the house temperature at 68 degrees when we are home and lower when we are gone.
In Michigan, the right thing to do is inescapably to heat the reptile room in the winter.