I want to add a entry door in the rear wall of our 5th wheel

A friend hasd a toy hauler over looking the Deschute River in Central Oregon befor he built a cabin on the property. He framed in a patio door like Roger suggested, then would pull up the door to protect it whil away. The only time the trailer moved was when they sold it. What they loved was the view it gave them then when there the back ramp was their deck.