Nice work on the combo rack, sacdan. Do you have any trouble with side-to-side movement while underway? The reason I ask is because I built a vertical storage rack for our kayaks (Sundolphins, just like yours). It is just a 2x2 square steel tube column with two 3/4" sch. 40 pipe horizontal bars to hold the kayaks. The rack mounts in the receiver hitch in the back of our 5er. I found there was quite a bit of side-to-side sway and had to add extensions to the trailer frame on either side of the hitch receiver to use as anchor points that I could tie the column to with ratchet straps to eliminate the movement. Think of a triangle at the bottom of the rack, with its apex about 1/3 of the way up the column.