I own both 40* and 20* HG Incubators. I really only need the 20* in the Winter months. The 40* takes me down into the low 30's. It is notably smaller when packed. Unless you were planning to camp well below freezing I'd suggest a 40* Incubator. Use the savings to buy an underquilt protector. For your location, a 40* Incubator an UQ protector should keep you comfortable over a pretty wide range.
Good Luck
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