Weekend Project- Old and new boardwalk scraps

So this weekend my brother asked me to help him put something together. He lives in a town that was devastated during Hurricane Sandy. Almost all of the boardwalk was ripped off and he grabbed a good amount of the scraps that washed up by him. The city allowed the residents to grab whatever scraps of the new boardwalk they were building. So he has a pretty sweet stash of old and new planks. He wants to make something like a 3' boarder in his garage which we are rebuilding into a tiki bar.
My question is, what do you think the best way to make this? He doesn't want to just nail it directly to the sheetrock. I was thinking of finding a placement he liked of the wood then nailing that to some plywood and then anchoring that to the studs. The studs are aluminum. Then trim it out and make it nice.
Any thoughts or ideas are greatly appreciated. He's also not really handy with tools, so I'm kind of on my own.
Thanks

 

I'd say something like this.....