Ours is more of a luggage rack, but maybe will give you some ideas. We kept it really low to the bus roof, because we were shipping it overseas at one point and every inch matters when you RoRo! It is very very sturdy. The front has the spare tires mounted on it and the back has been used for extra storage, but also makes a great vantage point. We used bed rails and perforated sheet steel for the racks, and rebar and rails for the ladder. The rebar is a little hard on bare feet, we added some foam pipe insulation to make it softer.