Does anyone have any of the extendable toddler bed frames from Ikea? Would a crib mattress work with in while it is in the shortest position or would it be too slim? I am trying to decide between converting our crib to toddler bed (which I don't love as an option because of the way that it converts) or buying a bedframe from Ikea. I am having a hard time being able to tell what type of mattress they use online and Ikea is an our away!