Cut a smaller piece of cardboard 8" by the width of your wagon. Use hot glue to connect the two larger cardboard rocket rectangles together at the back end, with the smaller rectangle in the middle. Measure how long this connected piece is (the entire rocket ship back).
Apply a line of hot glue around the outer edge of the backside of the nose cone and slip it over the front of the rocket, curving the half circle over the top front of the rocket. Press it down firmly for a few minutes allowing it to set.