yep all bolts..

I've got yakima lowriders w/ round bars attached to the stock roof rails




have the lights mounted on a piece of piece of right angle aluminum



i have 2 pieces of 1" square aluminum tubing mounted the the underside of the round bars, using yakimas snap-arounds


Ive got long bolts that come down through the rectangular hole (using washers on top of the snap around, under the snap around and under the square tubing).

attaching them to the front and back crossbars makes them really secure, then i just drilled down through the ends (as far back as possible) to attach the piece of aluminum with the lights on it.. and voila.. i had to trim all the bolts so they didnt stick down too far and contact the roof.. now i have at least 3/4-1" of clearance under each bolt.. plus i covered the bottom of all the bolts with a rubber cap just in case




also have the yakima loadwarrior mounted above all of that.. but i could take the loadwarrior off and leave the lights if i wanted and vice versa, they are independent of each other

ive used this setup offroad on more than one occasion as well as on the streets of philly (much bouncier than any trail ive ever been on!) with no problems at all

ill try to make an autocad model of it so its easier to see..