I think there are some portable DVR setups. I found some recently while looking at security monitors/systems (they also have multi-camera things that put all the shots on one screen, which I was thinking to use for multiple boats/cameras on wireless transmitters with the recorder on the PRO boat

I'm sure BK can build something for you. He's all electrical like that (weren't you a rocket scientitst too? Or the guy who built Ironman's Jehrico system?)