Last weekend I mounted PA cradles onto my old boat trailer. The conversion was pretty simple. A bit of a crude job, maybe, but I think it will work.
The only modification needed for the trailer concerned the supports for the bunks, or runners. They were angled towards the center. I needed them to be vertical. A little work with a file on one side of each top hole let me re-mount the brackets vertically.
I used treated 2x4s for the frame. Galvanized lag bolts were used to attach the cross pieces to the new bunks. Total cost minus the cradles was only about $30
Ready to go.
The only tricky part was angling the cradles properly to match the curvature of the hull from bow to stern. For some reason the cradles are engineered with only a slight angle, not nearly enough to contact the hull evenly. I used plastic shims to solve the problem. By looking at the degree of compression to the carpeting on the cradles after a few days, I would say I've got the angle fairly close, good enough, at least, until I find a better solution.
Hope these pics are helpful to some of you PA owners whose boats need a safe place to rest!