While not for monitors, my day and night cycles for various critters is often managed by 12hrs (or so) of my MVB. This is run on a timer. When it goes off, my CHE turns on (provides heat, but no light). If I want light for display purposes at night, I may use a red bulb...

For the the times you want basking spot hotter than the MVB can provide, or a boost in ambient temps, the CHE can be left on 24X7. Then the day is MVB + CHE and the night is just CHE (you get a night drop, but still stays warmer than room temp).