I bought the Thule ones and am very happy with them. However, for storing the kayak I made two cradles from pine padded with carpet that work well and you could do a similar thing for your cartop. To custom fit the saddles use the closest form station for a rough cut and then scribe them right on the kayak hull. You might want to use some closed cell foam for padding since it is probably better at absorbing the stresses of cartopping. The way I made mine was to cut two pieces for each saddle about 22" long by 5" high and then form the saddle curve on the top half of them. Then you put a spacer between them as wide as your Yakima bars and glue/screw the spacer in the middle so that it they will sit over the bar and extend down below it. Drill some holes for bolts below the bar and you are all set. Attach webbing to the two ends of the saddles with a buckle so that you can buckle in your kayak (I like to do both straps and bungies just to make sure whe cartopping).