yep, red scotch pad and truck bed coating from Duplicolor should do the job,
http://www.duplicolor.com/products/truckbed.html
just about every parts store and Wal-Mart has it both aerosol & gallon,quart cans, I use it all the time for touching up wheelwells,frames and bottom of fiberglass body kits, very easy to use, dries fast ,easy clean up and once dry,pretty nice finish,obviously it's nowhere near as durable as spray-on truck bedliner, but it's much better than asphalt & kerosene mixed junk some companies try to push as undercoating that will dry up ,fall off or get hosed off