I was able to obtain a set of memory foam toppers from a carpet flooring pad company a few years back to use on my Irwin 37CC. I couldn't have been happier about it. There were about 6 other boat's in the marina that I was able to hook up also, one boat owner had a bad back and he just couldn't go sailing anymore, but after he had the memory foam he was able to take a long awaited trip for a week or so and he didn't have any problems.
The one thing I would make sure of is that the foam topper is a true memory foam and not just a slab of regular foem. I also have a mattress pad to top off the pad's.
To cut the pad, use a really sharp knife, another boat owner tried using large sizzors and the pad had really jagged edges.
s/v Blue Bayou