This isn't what you are asking, but I also have longish very fine hair with an oily scalp and I haven't had any luck with the no poo/vinegar rinses with my hard AZ water. But, I finally tried conditioner only washing last month and am loving it! I resisted trying it because I was sure that conditioner only could never work on my oily scalp, but I finally tried it and it does. My hair is not weighed down by the conditioner, its soft, and my scalp isn't oily.
I still intent to do some experimenting with different conditioners. I keep hearing recommendations for really cheap conditioners, but I try to use more natural products. Right now I am using http://www.vitacost.com/Mill-Creek-Biotin-Conditioner
Ignore the ingredient list there though- it does NOT have parabens. That list must be old. I also tried a Burts bees conditioner that works ok, but not quite as well. It weighed my hair down more, but did still clean the scalp well.
I'm afraid to use conditioners that are too natural as they seem to have more oil which does not work on my hair since its so fine. I'm looking for a good middle ground. I keep meaning to start a post asking for conditioner recommendations.
Hope you find something that works for you. If you find a vinegar ratio that works I may try it again.