I had the local welding shop make up a lightbar/headache rack for me out of 2 inch square aluminum tube and 3/16" plate for my '01 2500. I have it all bolted on now and have the lights mounted, I must say these monsters are impressive. Nine inches in diameter and ready to make sunlight.
I have two switches and relays so I can have a choice of one light or two; I am using two different filters on them. I spent about an hour looking for a place to install the switches, but no-joy on an easy location. I finally settled on the knee plate below the steering column as least likely to cause difficulties. Took me an hour and a half to fit the two lighted rocker switches into rectangular openings I made, but they sure look factory. The hassle I am not looking forward to is getting the wire loom through the lightbar.
The relays I am going to put in the engine compartment in the corner next to the hood hinge mount. This will be close to the main power bus and in a spot I think will allow good visibility, but not be in the way of stuff flying around or getting too hot. I will post pics once I get done.