I recently got one of those little lock boxes that real estate agents use, you know the type that hangs from the door knob of the house? There's a combination on the front, and inside there's room to hide several keys. I have one at the side of my house attached to the natural gas pipeline. There are also some lock boxes that can be attached with screws to a post. Of course, this will only work if you live in a house. I'm not sure this would work in a high rise apartment building!
But you could also put a spare key to your van in that lock box, so if you're locked outside, you have a key to your house and your van. They're weather resistant to rain, but I don't think they'd hold up to road salt used in the winter in the rust belt in case you're thinking of mounting one of these under your van somewhere.







