My friend and I removed the 3/4 plywood from back ramp door and filled the spaces with foam insulation like we did with the walls. Later that day we swapped the 3/4 plywood from the rear door of the cargo trailer for 2 sheets of 3/8 plywood at another buddy's house and installed the 3/8 plywood on the ramp door.
Click HERE to see a slide show of the photos from this post.