Even Black dog plates attach to the engine and when you strike a rock, there is no magical place the force goes but into the engine. My plate or someone else’s. If there was a frame rail, then the force would be transferred into the frame and the engine would be isolated by motor mounts. The secret is not to hit rocks at all.
At least back is bolted to the frame. But like I said, you dont need to ride any hard stuff to fuck up the case (watch the video in my previous post).
Hopefully you can get it welded on the bike without having to split the case.