From the pic I cant tell if it attaches to the bedside on only the passenger side, or if it swings out both sides. so the tire is on one side and the can swings out the other. I would also like to see how you attached it to the bedside.
I think that I would make it into the tail gate, instead of an additional swing away. Build the hindges into the bedside and just skin the inside of the gate to secure everything.