I wish I had a picture (but I don't) with it mounted on the rack/Jeep but I made this support rack which helped a lot.
I used a 2" piece of Aluminum block which slides in the reciever hitch and drilled and bolted a piece of 3/4" galvanized pipe on the other end. Then I made the saddle for the yak to sit in which also helps when loading/unloading to keep the yak from falling from side-to-side. I welded mine but you could use threaded fittings if needed.
Note the 1/2" PVC pieces with the rope running through it. These are tied to the side of my roof rack/support pole to give it some front to back stability and some side-to-side stability.
It takes me all of 5 minutes to install/remove when not using the yak and took a lot of the weight off the carrier racks. I can cinch the yak down good on the support rack for piece of mind when hauling it.
LiftSaver Trolling Motor Mounting Bracket - Patent Pendingwww.liftsavertmmount.com
Works with MG Xi5, Xi3 and MK Terrova, Ulterra, PD V2 and Riptides as well.