My R1's the heaviest of my mid-layers. I only take it if I need it during the day while hiking, and it has to be pretty cold for that.
For camp, down to 40, I would take my Montbell UL inner or my Nano. Both work well paired with a light merino baselayer (which I always have for sleepwear.)
Respective weights (women's medium):
5.7oz - Montbell UL Inner jacket
8.5oz - Patagonia Nano Puff pullover
10.0oz - R1 pullover