The white two layer fabric is recommended to have a lining fabric
It weighs 1.6 ounce per square yard, if you use .9 ounce fabric for a lining the total would be 2.5 ounces per square yard
I used what I think was 2.2 ounce per square yard, but I don't know anywhere you can buy that
Quest has 2.5 ounce 2.5 layer WPB fabric, but I don't think it would be quite as waterproof and breathable as eVent
So, the white plus lining ends up being a pretty good solution.