20-23%. Got some really nice flavor from my last attempt but want it to be stronger.
I think the major problem with what you want to do is the amount of oil and what it does to yeast fermentation. Maybe a few examples will frame the issue.
When I was concocting various Papa John's clone doughs, one of my experiments was to make a PJ clone dough that fermented at room temperature for about 24 hours. I described that clone dough at Reply 35 at http://www.pizzamaking.com/forum/index.php?topic=6758.msg60197#msg60197
. If you look at the dough formulation in that post, you will see that I used a bit over 7% oil. But the yeast (IDY) was only 0.01250%, or a bit less that 1/64 teaspoon for a dough ball that weighed a little over 22 ounces. That dough was made in the month of July, which is often the hottest or next hottest month in Texas, but even if I adjusted the amount of IDY upwardly for a cooler temperature, the total amount of yeast would still have been very small. But in both cases, 7% oil would not impede the fermentation process.
Now, fast forward to some of the experiments that Norma and I and other members conducted on the Home Run Inn clone doughs. In the later experiments in the HRI clone thread we used about 19% oil. But the amount of yeast was about 2% for IDY, about the same for ADY used dry, and about 2.5% ADY if rehydrated. These amounts were for doughs that were cold fermented for about 2-3 days. What was especially interesting is that the doughs after 2-3 days of cold fermentation were firm to the touch. They rose but they didn't blow the lids off of containers. I might add that the use of ADY was mainly because ADY has more dead cells than IDY, which we believe provided more flavor to the finished crust, especially in light of the large amounts used. And I don't recall an alcohol odor.
My takeaway from the above experiments was that very large amounts of oil can have a major effect on the fermentation process. But it is hard to know how to apply the lessons we learned to your specific case. For example, if we had used 20-23% oil for the HRI experiments, we most likely would have had to increase the amount of yeast to compensate for the higher oil levels. Say, it is 3% ADY (prehydrated, not dry). From there, you might scale that number back for a room temperature fermentation of 24-36 hours. I'm guessing here, but maybe something like 0.70%, or 1.4% if using fresh yeast. Ordinarily, that would be a large value. But it has to be high enough to work while under the influence of 20-23% oil, even at room temperature.
One way to answer your own question is to simply try out a value of cake yeast and note how the dough behaves over the course of the 24-36 hours of room temperature fermentation. You should note the room temperature at which the dough ferments and when the dough reaches a certain stage of development, such as a doubling of the dough. You should note how many hours it took to reach that point. With that information, it might be possible to come up with a better number to try for the fresh yeast.
Of course, another possibility is if another member has made deep-dish doughs that were fermented for something like 24-36 hours at room temperature and can provide some guidance on the amount of yeast to use.