I think I've got it. Something called AMP-SUPERSEAL, which I gather is widely used in cars and consequently super-cheap online. You can even get all kinds of rubber housings for it if you want to get extreme, but the basic 2-pole unit looks like enough for me. I know that the ciggie plug thing can be made to work, but it's partly an aesthetic thing and partly size. We sometimes go tent camping on the Dutch coast in my little Alfa Romeo wagon, and we number five including the Au Pair. The glove box in that car is exactly what it says - just big enough for some gloves and a few maps! Get a bigger car? Sure, but my parking spot in central Cologne is just big enough for the car I have, and I'd rather drive an Alfa than almost anything else with four doors.