Been there, done that. I wouldn't bother with them now that I look back.
But, to answer your question: There is a well between the sideskirt and the rest of the body that works well for mounting, in the rear its kinda tough, but the bumper support works, and the front valance can hold the front one
when i was dumb and installed these i just used zip ties...dont remember to well but i dont think i drilled anything!
zip ties work well for the front and rear tubes, I found using screws to secure them to the rocker panel was the best on the sides.
I suppose I grew out of them, decided I'd rather have people look at my car because of the obnoxious s/c whine then because of a glowing underbody![]()