Like RamblinRev said...the HHSS (overcover, undercover, underpad) are a source of debate here often.
I used mine two weekends ago in temps down to 22F with 30-40mph winds, for two nights. This was in conjunction with a 20deg sleeping bag, fleece liner, and poncho liner along with the undercover/underpad/space blanket combo. I was quite warm, but many others have had issues at those temps or even higher.
One other thought...post for a bit here on the forum, see if there are any forum members near where you live...perhaps even a "hang" in your area that you could attend and try out all sorts of gear.