Let's start with the SE and see what we can do to make it lighter without reducing comfort.
1) Loose 10lbs from creative subframe/fuel tank combination?
2) Loose another 10lbs from simplifying the exhaust with a 2-1
3) Loose another 10lb from engine weight
4) Another 5lbs from redesigned frame+swingarm
5) Add 5lbs for some sort of simple rally fairing ala raiddesigns
So, (maybe I am gallant with the lbs) it seems that a 185 kgs 700/800 twin is possible, fully fueled and with lower CG than the SE.