Another Line-X fan here. I guess mine is UV stable because it has never chipped or peeled off. My daughter had one, I put one in my '08 and when I got my '17 I put another one in. I haul firewood, lots of yard waste and an occasional load of gravel.
I also bought a rubber matt for the bed. It sits on the sprayed in liner, holds things in place and is much easier on the knees. It is a bit of a job to remove it now and then to clean out the bed but I don't do it that often.
If I had a cover on my truck and never used it to haul wood and rocks, I think I would go with the carpeted bed mats people talk about. They sound pretty nice.