DD has just started crawling and we're worried now she'll crawl off the bed. Not so worried about night time as she'd have to get past us, but concerned about her day time naps. She's in a side car cot bed with the fourth side down (Ikea Gulliver). We tried putting the fourth side up but she hated it as the cot became too small for her. Kept wacking her head on the rails and waking up. Also kind of kills the whole co-sleeping thing. Would one of those bed rail thingys work?