Undercoating or similar in fender wells?

I’ve read on the forum from a few years ago about guys trying different stuff on or under the fenders. I was thinking about putting something like Herculiner on the underside of the fender wells to help protect them from rocks and debris. Maybe even Line-X would be considered. I think it would help keep the rocks from getting thrown into the plastic and breaking or cracking the plastic. I know Line-X is very strong stuff and Herculiner is pretty good too. Has anyone else used something similar for this reason and how is it working? Pics would be great too.