I might try a King size sheet on it. We just had an old double sleeping bag on top of it, lay on top of that in a double sleeping bag. I didn't put anything underneath it or anything on top of it and didn't feel any cold. I have a lovely spare tent carpet now though so I shall put that underneath. We found that it needed to be in more than one room of our tent with the divider zipped up.
Had one 2 years ago from Aldi - lasted 2 weeks and punctured - no comeback after 3 months (it was bought a few months prior to be used) so total waste of money
Amazing family weekend with old steam engines, classic car displays, market stalls, and full catering and bar. And camping on site - Save £25 by booking in advance.