I have had some question about my Hobie Trailer. I bought the trailer several years ago at Harbour Freight to carry several conventional kayaks. Originally I decked over the frame, and added framework to carry three kayaks. When I bought the TI the boat was much longer so I had to move the forward post as far forward as it would go.
To make the main bunk I used things around my garage. I bolted angle iron frame to the top of the trailed deck. Two 2x4 PT board are laid on each side, slightly angled down. Polyethylene Lattice is screwed into to the wood with a slight dip in the middle. The with of the bunk is based on the with of the Lattice, 2 Foot.
The two forward posts are bow supports from the original design. I can carry my new AI on top of the TI by mounting a rear support frame. This supports the AI without putting any load on the TI. Below picture shows the two boats loaded.