I have never tried anything like that, but how about you cut the hole the size you need it, then cut a piece of plastic "door/cover", from a spare bin or lid, that is a 1/2 inch larger all the way around. Then make a "U" shaped piece that can be riveted to around the hole so that the 'door/cover' can be slid in behind the U frame, but on the outside of the hole. This would give you a sliding door without the need of hinges or other hardware. Just a few rivets.

Keep in mind, I am not a graphic artist, but I made this as an example...



You could then use a small knob with velcro attached the sliding cover/door to make a nifty handle.

Rick