We travel in our DP motorhome with our 20-month-old daughter. I cut a piece of plywood that goes from the passenger seat to the dash and keeps her out of the stairwell, as well as away from the door. While we have a stair cover, it's pneumatic, so it won't continue to function after we're parked for any length of time. Plus that still gives her access to the door, and she's becoming quite adept at opening darn near anything. :) The plywood works great, and is easily stored behind the passenger seat when not in use.