my interest was peaked when I came across this conversation a while back. I've since gone in my own direction and come out with some fantastic results. I did find a couple of 12volt wireless headphone systems that come with a transmitter that gets audio from a tv, laptop or whatever audio device you plug in and two pairs of headphones. http://www.12volt-travel.com/12-volt-tv-accessories-wireless-headphones-c-689_756.html
Mine is the two channel variety and each pair of headphones can listen to a different channel. So while my grand kids are watching a movie my wife can listen to her audio books and I get the FM radio and a steering wheel. This was very easy to set up and is also very easy to use. The headphones each have control over which channel they are listening to. They also have their own volume control and they sound great. The transmitter is wired into the 12v dc power system or can be rigged up with a cigarette lighter plug. It gets the audio from the tv or audio device with an audio cable. This is a top quality system I'd recommend to anyone in an MH.