Park your travel trailer on a flat surface. Measure the width of your trailer door and the distance between the door and the ground with a measuring tape.
Cut two bases out of plywood using a circular saw. The width of your steps should be the width of the door, and the tread depth can be about 10.5 inches, per OSHA standards for a safe stair tread.
Cut the "riser" portion of your steps or what will be the sides of the two boxes. For the higher step, cut four boards that are 6.5 inches lower than the distance between the trailer door and the ground. So, for example, if the space between the door and the ground is 18.5 inches, the height of your higher box will be 12 inches. The higher step's front and back board width will be the same width as your door, and the two sides' width will be 10.5 inches. The lower step should be about 6.5 inches shorter than the first one. In our example, the lower step boards would be 5.5 inches in height.
Use a drill and screw to build two boxes with the lumber you cut. Secure the bottom plate to each of the walls with at least two screws on each side. Secure the walls to each other with at least two screws, one on the top and one on the bottom of the walls.
Turn the boxes upside down and place them one in front of the other so they appear to be like stairs. Using a drill and small screws, install the main portion of a sliding bolt assembly on the taller box, with the smaller portion of the assembly attached to the smaller box. Slide the bolt into place to hold the two boxes together. For extra security, install another sliding bolt to the other side of the steps in the same way you installed the first set.
Cut a piece of self-stick tread material with scissors and adhere it to the top of the boxes, where you will walk when the trailer is parked.
