Has anyone bought a captain's bed for their toddler? We have small bedrooms and really need the storage space under the bed and I don't want to have to buy two beds--one that is really low to start and then a captain's bed later on. My dd is tall, but I'm concerned about it being too high even with a rail and some pillows on the floor just in case. For those of you who have already made the switch, how high are your twin beds?