They're bloody tough little bikes alright. If you put a hole in the sump and lose your oil you can run them on two stroke.
You can get these handle bar clamps for dirtbikes and quads. Haven't tried them out yet though.
You could get a Kolpin hardcase that have an inner removable softcase. More secure and weatherproof but will be slow on the draw.
Then there is the sling. Keep the rifle slung across your lap.