I am interested in buying one for a present, but the mattress looks a bit thin for a toddler. I would like to know if anyone has used any extra padding, or different bedding safely with this product. I have read that it isn't recommended by the manufacturers, as the inner liner needs to be secured inside the tent, with the inflatable mattress in a pocket underneath. How do you then change it if the child is sick or has a nappy leak, if there is no spare, and these seem not to be available as an extra? Any ideas would be welcome, as the information I have read is rather unclear.