Just remember it has a small explosive charge in it to pretension the the seat belt (pull it tight) in the event of a crash! This means the the belt locks before you move very far so are less likely to get whiplash etc.

I would not advise leaving it tucked away - having tested them on a concrete garage floor I can tell you you would not want it to whip round and hit you!

I would advise going to the resistor route!