My uncle did PH work in Rhodesia/Zimbabwe for many years. He taught me to put a rifle in the middle of the vehicle if possible, and facing forward or rearward in the vehicle but not across.

His reason was that the middle of the vehicle was the most stable point during travels. There was a smaller chance of the scopes being bumped out.

When we travel with rifles (hunting etc) it will create quite a stir if everyone does the toilet-colddrinks-chocolate run with a rifle over the shoulder - even bagged. One stops on a remote corner of the parking lot (difficult to approach) and one or two people always stay nearby.

When one needs to move multiple rifles and it is impossible to do it at once, a similar situation applies. Two people work together, one stays near the vehicle.

I have not traveled really far with rifles many times but I make a point of keeping rifle and owner together in one vehicle. A friend got in severe trouble because his rifle was in the other bakkie which got searched in a road block.