I'm really surprised how popular it has become. Reserving 11 months in advance leads to a lot of plans being canceled and sites popping up at random times.
True. In AB it's a 3 month rolling window I believe. People will sell their reservation online if they can't make it rather than outright cancel it. Perhaps a new feature for your site? Rental sales (?)...or sub-rentals? Not sure what you would call that :)