Why not use an old rubber mudflap or two? Just another thought to the mix.

 

I have the tool box drawer liner that they sell at Sears in my cross bed and it moves around too much, I don't recomend it. But I did see this today at Genos, might be what your looking for

 

My local Ace hardware has rolls of slightly corrugated continuous rubber floor matting. I've used it on rolling tool cart tops, lining drawers that need heavier protection, etc. Not as thick and heavy as the conveyor belting I got from the defunct copper smelter (about 1/2" steel reinforced, had to use abrasive skill saw blade to cut), but definately more protection than the lightweight foam stuff they sell at sears. Comes in about 3 foot roll, just buy by the running foot.