While not a fan of bed liner stuff on a boat, many have used it, and does work. There are several non-skid paints out there and have been used for many years. I would recommend a paint before bed liner, only because there were designed for different purposes. The key to all applications is the prep work. Use to paint the decks in the service, just mask off, paint a real think coat of paint, then throw sand all over it. Once dry, hose it off, it looked great, and would last a few years before needing to do it again, but this was also a steel ship.
I wonder if anyone has ever tried mixing silica with 2 part epoxy paint. Once the surface is prepped, the epoxy will bond and last.