I built this trailer for a friend to haul her new Hobie Kayak and her bike. the yak sits on the left, and the bike o nteh right. She has a new Jeep Wrangler soft top and was severely limited in options to haul the new boat. Couldn't find any roof racks that would have worked for her. So I told her to go buy a cheap 4x6 utiltiy trailer and I would build her a crib. Originally planned to use 2x4's, but even with a small rack, it might have been to heavy for her. Built it using 2" solid core PVC pipe that is U-bolted to the trailer. This thing is very light weight and seems to be very strong. Holds her yak and bike perfectly and she can move the trailer around her drive and garage with ease. I have about $200 in PVC and hardware invested. After the pics were taken, I zip tied foam pipe insulation everywhere her toys contact the trailer. I also busted my good drill bits so I used wood blocks to anchor the eye bolts but I will eventually change that and anchor those directly into the angle iron trailer frame. She has used it a few times and so far so good. We looked into some dedicated kayak/bike trailers but they started around $1000 and some were over $2000. This was a lot cheaper option, plus the crib is easily removes and you can use the trailer for other stuff when necessary.
I have another 4x6 trailer laying around out back that never gets used since I have a bigger trailer for the SxS so I may make another crib for myself.