>using my new Hennessey for the first time
>ll start with the hammock + CCF
Most any CCF pad (I'm partial to the Gossamer Gear ThinLight in Wide or Wide/Long) will get you through the night at your predicted temp. I'm comfortable with a sleeping pad to about +45F (or a bit lower depending on clothing). You may have some condensation underneath you, so a top quilt will work a bit better than a sleeping bag.
I have the JRB Nest, which is the same as the No Sniveller except for a different slit design. The Nest is designed to match the Hennessy Hammock entrance slit, but I've only ever installed it that way once, and I had some cold drafts come though the slit when I moved around. Since I use the Nest underneath the hammock in winter, most of the time I just close the Nest's slit and slide the under-quilt to the side to enter, the same as you would have to do with the No Sniveller. (I have a thick synthetic top quilt for the winter.) I'm thinking of buying a JRB Old Rag Mtn for next winter.
In warmer weather (freezing or above), I generally use the Nest as a top quilt and the Hennessy Hammock SuperShelter under-pad and under-cover combination for my under-insulation. (These have the same weight and bulk as the Nest, though.) As a top quilt, the Nest and No Sniveller are equivalent.
I think that after you've spent a night or two trying to keep an in-hammock pad properly arranged you will understand the popularity of slung insulation. A hint on using the pad: roll it about 1/3 of the way up, place it in the hammock with the roll at the bottom of the slit, sit on it, lay back, lift your legs, and unroll it. Once you figure out how much to roll, this is a straightfoward way to get it arranged underneath you. This is much easier with a top quilt than a sleeping bag.
An option which I haven't tried extensively is to sling a thin sleeping pad underneath the hammock using a JRB Weather Shield bottom cover (9.5 oz). It's more convenient than having the pad in the hammock but I'm not sure how well it works in a breeze or if the comfortable temperature range is the same as using the pad in-hammock. I need to do more testing. Using a sleeping pad does allow the simple option of going to ground with the Gatewood Cape or pitching the hammock as a bivy, and a pad/Weather Shield is significantly lighter and cheaper than Hennessy's under-pad/under-cover solution. (The Hennessy under-pad is open-cell foam so it's useless as a ground sleeping pad.)