I wouldn't do the bedliner thing, unless you have an offroad paint job.
You can get some clear plastic self adhesive sheeting that is intended for applications like this. Cut it to the shape you want-
Some of the older trucks came with this in front of the rear wheels just for this purpose (like '81 GMC). I have used it to protect the paint below the fuel filler on my old Camaro, etc. It's hardly noticable.
Can't remember where I bought it, a small roll. Probably an autobody paint supply place IIRC.