tailgate ramps

bought a pair like these without knowing they want to drill holes and put pins into the tailgate to hold them. instead, I used tool box liner folded around the gate. moving a running snowblower this way was easy and nothing slipped.
https://www.harborfreight.com/18-inch-x-72-inch-mesh-nonslip-drawer-liner-67055.htmlthese were the aluminum "kits" I bought along with 6 foor 2 by 12's. now, just need to figure what to coat the ramps with to keep them "grippy" if used in wet/damp weather.
https://www.menards.com/main/search.html?search=ramp+kitsorry, other link did not work. used the 12" ramp kit