A good 32-F rated bag should be fine - as daddytwosticks says, make sure you have extra clothing in case it's chilly. Now, I've had some "32-F rated" bags that were not even close, but we don't know what you have to comment.
I have a Western Mountaineering Megalite, which is a 2-lb bag rated very conservatively to 30-F (which means that in my long johns and a light hat I am warm down into the high 20s. YMMV.) It's a great bag and still in perfect condition more than ten years later, but man those things aren't cheap.
Any 2-lb bag rated properly to 32 is going to be high quality down with a very light shell fabric, so none of them are cheap. Sometimes the Marmot bags are on sale. Also check the Montbell #3 bag, they are occasionally sale priced.
Edit, okay you want a 20F bag under 2 pounds. (We posted at the same time
)
Western Mountaineering Terralight is new, rated to 25 degrees, total weight 29 ounces.
WM Ultralite is a sweet bag, though it's a very slim mummy. 20-F, 29 oz.
The Alpinelight is the wide version of the Ultralight, weighs a couple of ounces more.
Good luck.