I have rather unique cargo necessities, since I am a technical diver and need to be able to transport a lot of gear to and from dive sites (where it's wet on the way back). My approach was to get the cargo cover to protect against water, and to build a much more solid platform on top of it to protect the cargo area from the abuses of loading and unloading dive gear. I find the bumper cover is very practical since things can scrape past the bumper when moving gear in and out (see pictures below).
Here's the finished product:
The 'front' view:
As you can see, everything is set up with sturdy hinges, so it can all be collapsed when storing in my garage.
With some stages:
And finally with a set of double tanks in the back:
These are all held in place with rubber straps, and don't move even on bumpy roads.
So far I've been happy with the cargo liner as a protector.