Can Bedrug be installed only on the floor of the bed and not the sidewalls?

But of course they can, they're held in by velcro and come apart for cleaning and then you just stick them back on wherever you put the other side of the velcro.

yes it can. i like mine alot so far. the only downside i have found is that when you try to take it out of the bed the velcro is stronger than the adhesive part on the bed so it rips it off sometimes...but thats only IF you want to remove it. I have never needed to completely remove mine.