Hello again @Rhubarb!
If you are interested in a Yakima set up, the Ridgeline System is what Yakima recommends! Similar to the Thule set up, you will have some decisions to make on which bars you'd like to go with. From there, they will recommend the appropriate feet or necessary accessories to complete your kit!
Let us know if you have any other follow up questions.
I'm looking at ordering the Yakima 55" HD bars SM-Pair and the yakima ridgeline tower. Will this work for the Yakima showdown kayak/sup rack? I have a 2017 ford edge. Also do i need to purchase separate ridge clips and if so what size?
Thanks for reaching out again. You’ll notice, I have moved your question here so that it is easier for you to have the majority of the answers in one place.
Here is what is specifically recommended by Yakima to fit your car. You will need the Yakima Ridgeline Towers and Ridge Clips. The clips are sold separately. You will notice the clip number for your specific vehicle is 36. This is not currently available through REI. I am sure Yakima would be happy to help you secure this inventory. As you mentioned, you’ll want the Yakima 55” HD Bars and Yakima also recommends getting the HD bar adapters to complete your setup.
I’m sorry but from all of the information online available from Yakima, the ShowDown is not compatible with the recommended rack solution for your specific vehicle. I apologize that it took us this long to arrive at this conclusion.
At this point unfortunately, reaching out to Yakima in hopes of a solution might be your best course of action. I’m sorry that I don't have any additional answers for you in this regard. And do not worry, you have not been a pain at all! We are here to help!