Mike,
I got 2ea 5x7 KC daylighters mounted up there.
I used the front bar of my Yakima rack to mount them, your stock luggage rack should provide plenty of support.
I prefer the Yakima rack because it has round tubes, this allows me to tilt my lights back (facing straight up) when I am not using them, so they dont get hit by rocks, or parking garge ceilings. Also the Yakima tubes are great for running the wires, drill two holes and fish the wires through, very clean install.
I drilled a hole in my roof, about 5/8" dia, above the pass side side view mirror for the wires, ran the wires (3, 1 ea +, common ground) up the winshield pillar, under the headliner and right to the base of the rack.
I used a rubber grommet to fill the hole with a bunch of clear silicoln to make sure. About once a year I strip off the old silicoln and re-do it just to keep water out.
It works GREAT this way.
2 5x7's with fog lenses make TONS of light. The headlights/driving lights do a good job of getting whats in front of me, so I tend to aim these KC's slightly left and slightly right, giving me a full 180 array of light, it;s like daylight!
It takes some getting used to them on the roof, they will light up your hood and anything in front oif you like dust/fog makes it a little weird.
I prefer the way I mount5ed my lights because they are not in a fixed position, by loosening a simple wing nut I can aim them up/down or left/right, even backwards if I wanted too.........plus there is still plenty of room up there for 4 snowboards..........