I have a 1988 21 foot Sunrader that I would like to put Yakima Racks on. I figured the best way would be to place these "wide body" brackets
http://www.backcountryracks.com/yakima-wide-body-bracket-8001.html
at the roofline and then attach a Yakima 1A tower system (these are the old-school gutter mounted original racks Yakima first started with).
The Sunrader has these Steel Beams that run along the edge of the roof that I would have to drill into in order to secure the brackets. Are there self tapping bolts that I could drill into these steel beams that would secure the brackets?