I use a mummy bag with a HH bottom entry. I just have the bag open inside the hammock, with just the foot box closed. I climb into the hammock, lay on the bag and zip up as required. Never really been a problem.
I used to use a foam pad, cut to mummy size (with added wings in the hip area) inside the hammock, but was a pain to be honest. It always seemed to want to escape from under you when/if you moved during the night. Now I use the HH SuperShelter and OverCover (when needed).