Positioning your caravan in storage

Hi all, my van sits on a compressed gravel standing in the storage yard, when the vans either side of me are out it's hard to establish where it should sit centrally in my bay to allow ample space for my neighbours.

When we were all parked I painted marks on the floor where the wheels (and nose wheel) should sit to ensure a perfect drive in every time. Its hard to shuffle around a twin axle!