It can be done, and with enough gear to be comfortable. I do it a lot, but not truly 3 season. Here is a sample with no cuben. The shelter would not have been appropriate in heavy rain or snow, as a bivy would have been necessary.
See Page 10
I now have a BPL Nano Tarp, and just ordered an Epiphany quilt. Also have a 1/2" X 19" X 44" PF Sheet, and a 1/8" X 25" X 74" PG Sheet on order from Steve Evan, so a ground sheet is not needed. This should be decent insulation in cold weather.
A Caldera Esbit Cone set up without the caddy comes in a under 3 oz, so hot food is also possible.
So why do it? Depends on the trip. This summer I am going to do a ~ 60 mile loop in the San Gorgonia Wilderness and climb the 9 peaks on the divide (10,500 - 11,500), and with the elevation gain of 6,000+ feet, I want to do it in 3 days. So it will be a good time to test a 3 season kit that is under 4 lbs.
How about a sub 2.5 lb kit?
Alan Dixon 2.4 lb