Consider putting it in a tank bag on top of some foam. Besides being more accessible, it will take less direct vertical jarring being away from the same vertical plane as either axle.
Excellent point lxdude, something I should have thought of myself. Not sure my tank bag is bag enough but I can certainly try it. If it will fit I can just cut a chunk of foam to fit and turn the tank bag into a fitted camera bag.
Various Canons and Nikons. A Mamiya and a Bronica. A couple Brownies, and a Couple of Argus' (Argi?)