We noticed a slight ripple in our 2007 vinyl floor covering within the first year or two. It's hardly noticable, but it is there. It has not gotten worse since. I wonder if the bouncing rig moves things around very slightly to create the ripple. Either the flooring is not 100% glued down, or the decking shrunk as is common with wood, or maybe both.
About runners and such, I bought rug runner material off a big roll at Menards for our outdoor storage compartment to protect the lower fiberglass surface. I had enough left over for that first entry step. I wished I had enough extra to do the rear compartment.