I think the kill switch is a good idea - hide it out of sight and it's a security measure, too. A friend of mine had that on his soft-top Jeep, a kill switch in the locking glove box.
I used to have this problem with an old car I owned, something was draining the battery slowly so if I didn't drive for ten days it would be dead. But now I own a new car, and drive it about once a week, so the battery is always good.
How often do you use the car? You might solve your problem by just starting the engine a couple times a week. Or, if you can jump-start it, park on top of a big hill.