Light to me is no camera bag. So one lens on a body. If I am trying for more flexibility, I attach a small pouch to a belt and carry either a second lens in that or a small digital second body such as the GRIII or NX Mini with the 9mm on it.
If I want lots of flexibility with super lightweight I can bring my Pentax Q kit. Showing M3 for size comparison.
That has an equivalent of a 40mm f1.9 prime, equivalent of a 23–70mm f2.8-4.5 zoom and a 70–209 mm f2.8 zoom. The M3 setup weighs 801 grams with the meter and Elmar on it. The entire Q setup is 549 grams.
Shawn