Thanks for the complements - In answer to the questions -I took out the headliner and drilled through the roof supports in the back. The middle rails sit flush with the roof, so it is bolted flush with some of the "camper strip" used between camper shells and truck beds in between.
The front "mounts" are bolts through the roof supports and then through plastic shims I got from the "specialty bin" at Lowes. I just ground the shims down to fit. They sit on rubber washers toped with regular washers.
Nothing techincal, but it feels very solid and was a lot cheaper and easier than the alternatives. Cost about $15 for the hardware and $125 for the steel/wire/primer/spray paint. God (and my wife if you asked) only knows how many hours, but it was my first welding/fabrication project so I took my time.
The roof supports sit flush with the underside of the roof and I used large washers there also. Because the rack sits flush, the load is spread over the whole roof. The rack weighs about 65lbs.
As far as trees - it will be interesting but the trips that I have planned right now are to AZ and the beach.
Light is on the way as soon as $$$ permits.