I am looking to add a two bar rack to the top of my pop up. However, I do have a challenge in mounting it, which I am looking to get some insight on. The edges of the roof on my 94 Coleman Columbia are curved. There is some hard wood material underneath the aluminum at the corners which I could go into for a secure attachment, but I do not thing the rack will sit well on the outside, with the brackets teetering on the sloped edge. If I go inboard a little, I am likely looking at bolts with plates to hold it. That said, I also have the 3/4 inch of foam to get plates above (or to squeeze with the plates/bolts... which doesn't seem an ideal option). Any thoughts or ideas here?