Not trying to put a damper on your project, sounds interesting!
Actually I would try and put a damper on this idea. Not trying to insult you in anyway or try and say you are not capable of designing and building a cruise control. Just think of all the possible downside risks you would be assuming Vs the upside gain. I'm a big fan of personal freedom and individual risk taking but there is such a thing as common sense and personal responsibilities also.
Lefty