SMB has a screen for the side doors, I sold mine because I didn't like the functionality. The same thing can be used on the rear doors, but there are a few problems. I bought some army surplus tent netting and rig it up around the rear door really easily, although I have a heck of a time getting the bottom of the side step/door well secure and am waiting for warmer weather to revisit the project.
More on the SMB solution:
viewtopic.php?f=7&t=3159&hilit=screen