You don't need a proper guest bedroom. If you've got a spare couch, futon, or even an empty stretch of floor, someone will be delighted for the offer! If you (and your housemates) are up for it, three or four people might be happy to sleep in your living room, or other space. It's not uncommon to offer space with the condition that guests will bring an air mattress or other sleeping arrangements. Let us know what you're glad to offer, and we'll start matchmaking!
Thanks for making Rose City Blues so welcoming!