Has anyone built a ramp to load a mower/4-wheeler that fits into a truck's 2" trailer hitch? I have looked at "Safe-T-Ramp" on the Internet, but I would like to build a ramp to load my lawn mower into the back of my truck and then have the ramp lay flat to become a "shelf" to carry a push mower or other equipment. I am thinking of making it 5 feet wide and 6 feet long. When it is laying flat, I'd like to made the last 2 feet of ramp fold up so only 4 feet is sticking out behind the truck. Any thoughts?