As far as magnets go, I saw that asked about mounting a cowl somewhere. The consensus seemed to be, if I remember correctly, that it would add more weight than needed and would not be anywhere near as secure.
I suspect that with some neodymium magnets you could get the size/strength issue down ok. Heck, you could probably find a set where the problem is that it's too hard to take apart. Not dure exactly what their weight runs, but the magnets are pretty damn small and strong.