Right now I'm leaning towards using the mummy bag I already own. It weighs around 700 grams and packs pretty small in its compression sack. The weather is warm enough right now that I figure I can just sleep on top of it, and wrap it loosely if I need to.

Then again, it won't take much to visit the local bed and fabric stores and plug in the sewing machine. The nice high-end gear linked above won't arrive by the weekend (my start date), sadly.