happyjack2 - In our unit the switch near the door turns the power on for the front overhead double bulb light. I took one of the bulbs out and replaced it with one about 1/2 the physical and brightness size. Works well for entry, exit, and low lighting while watching TV. I also wired the Fantastic fan into the same circuit. That way we can turn the fan on and off with the wall switch. I know what you mean about brightness. It turns the inside into daylight if you turn on all the bulbs - I think we have 12 bulbs.
Not sure on a dimmer switch, we'll have to have an electrical engineer tell us about how to reastat or resistance a 12 volt circuit.