Don't know if it would work or not, but Camco makes the propane tank cover for our travel trailer. The pop-up access door on top blew off soon after we bought the trailer. I called Camco, looking to buy one - the lady answering was extremely friendly and just dropped one in the mail to us for free. (It is now secured by a bungee)
I don't have access to the number now, but its worth a shot calling their main # from the web.