We purchased a Tear Drop trailer 2 years ago and it had those hard 4-inch foam pads in it. We tried it 2 nights and it was awful. We sleep on a waterbed at home (very 80's I know) so we bought a queen size air mattress. It sleeps like our waterbed and it doesn't develope "hot spots" from laying in the same place too long. They aren't expensive and we sleep great.
kathyd