-Synthetic bag rated to 15 or 20 degrees (I use a MountainHardwear Ultra Lamina 15).

-ThermaRest NeoAir X-Therm or X-Lite.

-Thermarest Z-pad.

The closed cell Z Pad will help a lot with insulation from the ground and comes at a minimal weight penalty. Doubles as a great glassing pad. Synthetic insulation is the only thing I'd consider in the Northwest. If sub 20 temps are expected I may consider a light sleeping bag liner as well.

Disclaimer: I'm just a Google Fu expert