Ghostbuster

My 81 CJ5 is bascally a daily driver. I dont take it off-road very often.
I am doing some body work on my CJ5 this summer. I have some paint bubbling
up with some light rust, in the interior under the seats. I pulled the
seats out and I am doing some sanding,
My question is this. Should I use Herculiner or some other roll-on
bedliner. Does it give me any added protection for future rust. Or am I
better off just repainting? And yes I understand that the underside rust
is a factor. I will attempt to clean up the underside and do a little
undercoat for protection.
Has anyone out there used a liner like this? Any regrets?

Thanks Brad