Thanks for the reply but I'm specifically interested in info about tintable undercoating/bedliner - and just how well it can be matched to the body color.
You will have to see what the manufacturer specifies. For example, when my buddy was selling Speedliner they reccomended PPG paint matched to the vehicle. I forget how much per gallon you mixed in but it didn't take much. I tried other paint on some side projects of my own and the color didn't keep for long.
Since you are wanting to coat the underside, UV fade will be minimized.
