They are not very comfortable to sleep on.  We use memory foam and a down bed on top of them.  I would buy the factory cushions and covers to bring your Scamp back to "stock", then get a memory foam to go on top.  I had slipcovers made for mine as a decorative thing, but kept the stock covers.  You could have custom cushions made, but without a pattern to work from they might not fit as well as the original design.  I imagine those factory cushions are expensive, but down the road if you sell your Scamp it would be a good selling point.