The biggest reason most makers avoid super lightweight bamboo rods is that the taper is so thin. If a bamboo rod has a tip diameter of...say, fourty thousandths of an inch, then the sections that make up the tip will be twenty thousandsth of an inch thick. To hand plane something that thin is quite tedious. I actually built a 1 wt. bamboo fly rod back in March for a fella to fish the brookie streams of the park. Talk about thin! If you are set on a light bamboo, I would consider a Devine Fairy which is a 7' 6" 3pc. 3wt., or a Heddon Extra Light Trout 8' 3pc. 3wt.
Hope this helps..