Mike --
They are very simple to make yourself. I put them on all of my trailers. For planks, I use 1" x 8" "synthetic trim board" which is made out of extruded PVC resins. There are many brands. I drill through it adjacent to the trailer frame and through 1 x 2 oak pieces about 6 inches long. I recess the bolt heads in the trim board and use washers under the heads. With the trim board above the frame as a walk way and the oak pieces crossing the frame below, tightening up the bolts holds everything firmly together and the walkway easily supports my weight (nearly 200 lbs.). I put the bolts and oak cross pieces about every 2 feet. The trim board can be somewhat slippery when wet so I use black 3M safety tape to reduce the chance of slipping. All in all, a very simple and relatively inexpensive project.
