I think your RV market is way to small. There are many other applications with no local power, such as construction site equipment and material protection - build the BOX and sell it and add packages with different levels of security and monitoring. Discuss your project with a couple independent security equipment rep's. One good one in the average state could be your sales force. I am sure you know the real $ is going to be in the RMR if you can get it going. Suggest you build in a delay between signals sent and local annunciation. If you try to get message out at same time as audible there may not be enough power for the message. Now I can take my nap.