I have decided to take a spare aluminum camper cover and take it down to the frame then create a dog topper with aluminum and tubing. The trucks bed is 72" L by 61" Wide. How wide should each stall be for a medium sized dog? I am thinking about using doors with louvers; ideas need for dividers. I am going to have a drawer system for storage and water tank. It will be going on a 1984 ranger 4x4.