I tried a Stephenson DAM in my Hennessy last summer. I kept feeling as if I were about to fall of of it. Of course, I did NOT, but I felt as if it might happen. The cross tubes instead of length-wise might help.

An Enertia Klymit crumbled up used on top of Hennessy's double-bubble-reflective pad, so I can't recommend it.

A NeoAir is on my list of things to try in a hammock, but mine is the shorter Women's version, not wider and longer as is Rick's.