...more at the other end of the scale...not pretty but effective....
It's main trick is that the entire windsurfing box, contents and all, can be hoisted up by into two over-arching frames, the trailer pulled out from underneath and restored to a conventional box trailer for landscaping and other typical trailer needs. I used 25mm tubing. I am certainly not a welder by trade or experience, but learned along the way. Buy yourself reasonably thick tubing (40mm square x 3mm is a nice size to work with that is easy to weld and hard to blow holes in), have a bit of practice, buy a $60 (on special) arc welder from supercheap auto, and you'd be amazed what a reasonable practical novice can achieve.
TIP - if you want to store your sails in the racks (as opposed to across the floor), buy some 150mm PVC pipe, cut into lengths as long as your sails, cut them in half laterally (so they are semi-circles in cross section, and you have instantly made great cradles that provide full length support and restraint to your sails (instead of having them sit on two cross beams that create localised pressure points on the sails). These aren't shown in the pics - they were a recent addition but can send photos if anybody doesn't get my written description.
Eckas.