Welcome to the site.
Our Sprinter is a 2018 so I'm not sure what all changed from 2014. I wouldn't take ours down any logging roads per say but we do live on a minimally maintained gravel road that's more sand than gravel after all these years. So every trip out and back it gets a little mileage on this terrain as we head to the paved highway. The usual pot holes, washboard, and washout ruts along the edge and our Sprinter is doing fine with that so far anyways.
I don't race down the road either more like 10-15 mph on average. I have more hassle with tree branches hanging over the road than the road it's self. Last year I went along and trimmed a bunch with a gas powered pole saw since the township doesn't do it anymore.
The 5th wheel had a lot more height than our previous travel trailer which was less bothersome with overhanging branches. I just have to be more aware now as I go. The roof membrane is in good shape and I'd like to keep it that way as long as I can.