Custom Gas Doors?

Who has em, Im looking for an idea for a gas door. My fuel cell is under the back of my bed.Im about to order a 59.95 Cool Cap, from Air Ride Tech? Since all there stuff is over priced im guessing this is a bad idea? Iv looked at a few other ideas.http://williamsstreetrods.com/fueldoors.htmlhttp://www.newton-equipment.com/

Im a little stumped on what way to go. Can people post pics? I need some new ideas!

an idea ive had is to have the filler and cap inside the bed. therefore the outside would be smooth, i havent done it, i havent even got a new bed yet