I had this problem too. I ended up buying a single size flat sheet to cover the mattress and a light cotton quilt from a chinese department store that has a nice country floral print. The quilt is machine washable and so big that I had a cheap tailor cut it in half and bind the edges. I now have 2 summer quilts. If my daughter has an accident with one of the quilts, we have the other. As for a winter duvet, that was a bit trickier. I bought an ikea single size duvet and a light quilt and doubled the quilt over to fit the bed. Not ideal, but I haven't found anything else to fit the bed here in HK. I might see how much the local tailor charges to tailor the quilt and duvet cover to fit the bed...She charged less than HK$50 to cut the summer quilt and bind the cut edges.