We've got two Yakima ski racks, one with the Mighty Mounts and one that uses the old-fashioned clips to wrap around the cross bar. They no longer make the clips, except for their round multi-use crossbars, having come up with the MM's as the all-purpose crossbar mount.
This is a shame because the MM's are a pain in the tush compared to the old clips. It takes far more time to put the rack on with the MM's... instead of hand-tightening one bolt at each of the four mount points you have to tighten three allen bolts at each (one blindly), with the mount sliding back and forth until secure. The only advantage of the MM's is they can be used on pretty much any crossbar, but are an expensive and awkward way to do so. It was better when you just had to buy an extra set of cheap clips when you got new car.
When used on our 2013 4R rack, the bolts holding the MM's are too long for the low profile crossbars. The bolts would drive into the roof to tighten them properly. Sooo... you also have to buy the bloody Yakima crossbars and their rack mounts for a bunch more money. BTW, our JX35 rack works without the extra crossbars, but our old clips fit it fine.
I don't know what Thule or someone else offers. I went the expensive bandaid route because we already had the Yakima rack and I wasn't smart enough to shop around, but in retrospect it would have been cheaper and far less annoying to toss it and buy someone else's system. A better way must exist; the Yakima method is awful. Good luck, and let me know how it turns out.