Mostly, your params sound like a UL tent with good ventilation and good condensation characteristics (hightlow vents.)
This opens up a world of possibilities. Tarps and UL tents in all sorts of configurations for you and your partner. Actually, a two man tent is very efficient in terms of space per weight carried, split amung two people. Most 2 skin tents weigh a bit more than your stated goal of 1200g (1.2kg or 2.6lbs,)though. Even a single skin Stephensons weighs about 2#11 or 43ounces. Good but the condensation is poor in a single skin configuration, and, heavier than you want.
Assuming a subtropical enviornment, I am not sure of some of your params. 250 fill?? Usually fill for sleeping bags/quilts is more than 650, often 800 or more. You didn't mention bug protection and is often a priority around 50-80F(10-25C.)
Six Moon Design, Bear Paw, TarpTent, Gossamer Gear is rummored to be working on a new design, lots more... All less than your required weight.