Use a warmer pad to start. It's AMAZING how much difference a good pad can make in your warmth. Remember, the pad can be worth 35% of your insulation.
If you like the P. Plus, go for the women's model... has an R 4.5 instead of 3.8; the Trail Pro women's is R 5.1, but adds ~7 ounces.
I'd recommend going for a down mat. Makes a big difference in warmth, comfort, packability. R 5.9 to R 8.