I would buy the electromavin camera I mentioned and a 11.1 v lipo battery. I would mount the camera on a servo and then mount the servo, camera and battery onto a piece of plywood. Then you can strap the set up on your plane with rubber bands with lots of dampening foam in between. You will need to buy adapters for the video and audio inputs from the camera to the AIPTEK camera. You will also probably have to solder an adapter onto the the power wire of the camera so it will connect with the lipo battery. Check out my first video where I show this set up plus a transmitter. http://www.acidplanet.com/artist.asp?pid=827877&T=7088
Your set up will only add about 5 - 6 ounches of weight. My set up is about a pound because the transmitter is heavy.
Good luck and have fun.
-Peter