I haven't a clue about bones and all that sorry mate. I literally edited Dyanamic/Static on those logs I swear it was that simple.
One of the values changes it ridged to not-ridged.
All the new corrugated pieces and a new rock done now and in game view:
Due to the texture and angle the rock isn't showing the edges much, it's a flat slate that juts out at random levels.
Slightly better angle on that rock showing the edges
Last pic for now, I'm done working haha. There's 4 more rocks, including a nice big boulder. Yes I'm aware the boulder looks like a Ferrero Rocher I may change the texture.
I am working on making the corrugated metal sheets react dynamically to the vehicle weight and position. So if you drive on a certain spot, it will rock back and forth until contact with the ground is made, just like real life!