I mounted to the rope rail on top of the tubes. It lets you have a wider canopy and gets it higher. But "you" have to pick the size. I was lucky and found on Amazon a $60. top that fit perfectly. It doesn't"t have Sunbrella fabric but its not up all the time and 4 years out its not showing any fade or wear. I used a scrap piece of plastic decking wood and made two blocks that pinch the fin of fabric the side ropes are also attached to. Regular hardware thats probably included mount to that.
Can't get pic to upload. PM me if you are interested in what the blocks look like.