I have recieved some feedback from both designers and builders. They suggest a range from 125 to 135Kg's as minimum weight. That weightrange is achieveable for a 20 footer with a jib both for manufacturing and homebuilding (in plywood if need be)in their opinions.
I would suggest a minimum weight of 130Kg's, based on that input.

Another issue, well debated earlier, is the 10 foot beam. It's viewed as an detriment for the average sailor Joe, not beeing able to put it on a regular trailor. Options are either a tilt trailer, disassembling, or some sort of folding/sliding mechanism. Personally, we use 1 hour to tear down our boat for travelling, and two hours to put it together again. We can leave the boat with the mast up at our club, so we dont rig the boat every time we want to go sailing.
Having sailed a cat with a 10 foot beam for some years now, I would not consider a high performance cat like what we are discussing here with a 8 foot beam. Even if it's more convenient when you need to trailer the boat around.
If assembling the hulls/crossbeams/trampoline platform is to much, I seriously suggest a kind of tilt trailor. There are many types of tilt solutions, but one of the best one I have seen used the area under the boat as a gear-storage/camping shelter. It looked kind of like a scewed metal tent, provided great storage and a place to sleep if need be, plus, I think it helped with the aerodynamic problems of trailering a tilted 20 footer (crosswinds and meeting trucks).