Jon,
The only thing i know of that approaches your specs is the new material being used on the W/B Black Diamond Tents, unless you consider also the material on the Marmot Membrain Strata jackets.
Don't know where you can buy either of those by the yard, and it may not make any difference, anyway. A strong argument has been made on this site and elsewhere that while W/B material works OK in clothing, where it is close to the source of the the vapor (your skin), it doesn't work very well at all from a distance, as with a tent canopy.
So ventilation and mesh protective panels are the only good answer for a single wall tent, so the argument goes.
At one point, I was sold on Epic Malibu (1.7 oz/sq yd), until I read all the accounts of its failure in prolonged heavy rain, which is my primary reason for lugging a tent in the first place. And BD has dropped it. Have a lot of it that I would be glad to sell you cheap if interested.
Am inclined toward thinking that the strong argument is right, and have focused my efforts on designing a single wall of non-breathable fabric with netting panels at the sides head and foot, and lots of ventilation. Tarptents are one example. I think this approach will be substantially lighter than a double wall, but of course will have much less insulative value, and no inner tent to catch and divert drips from condensation or leaks.
As you can tell from the threads on this forum, the ultimate light weight tent is still a work in progress, and nobody has all or even most of the answers.
Good Luck!
