i had thought about the drawer liner as an option, but as i had no experience using it i wanted to be cautious.
with my metal ramps, i have used thick old carpets, but even that can be a bit scary.
what i did with them was place against the lip on the entrance to my garage when i need to work under vehicles for extended times, unfortunately that puts me on the ground outside and with the mercy of the elements.
hope others can chime in on some useful experiences to keep them from slipping.