Out of curiosity, I wondered what water temperature you would need to make a dough at market at an ambient temperature of around 100 degrees F to get a finished dough temperature of 80 degrees F. My first thought was to use the table that RoadPizza provided at Reply 8 at http://www.pizzamaking.com/forum/index.php/topic,11726.msg108395.html#msg108395
and to assume that your Hobart mixer has the same friction factor, 25 degrees F, as embodied in RoadPizza's chart. Unfortunately, that chart does not get above 90 degrees F. So, I used the general method that Tom Lehmann set forth in the article at http://www.pmq.com/mag/2003spring/tom_lehmann.shtml
. Using Tom's calculation with a room and flour temperature of 100 degrees F and a friction factor of 25, I came up with a water temperature to achieve a finished dough temperature of 80 degrees F of 15 degrees F. That is considerably colder than ice cubes. Even if your mixer were frictionless with a friction factor of 0, which we know is not possible, you would need a water temperature of 40 degrees F.
My recollection is that many moons ago, when you asked me for help coming up with a Lehmann NY style dough formulation for use at market, we tried to calculate the friction factor for your mixer. However, I do not recall what that value was for the batch size that you had in mind at the time. Either way, I think you will have a hard time getting a finished dough temperature of 80 degrees F in your market environment. Some might suggest that you use frozen flour and a cold mixer bowl and hook/beater to solve the problem. However, when I tried that on a couple of occasions, I found that the flour rose to room temperature fairly quickly once it came out of the freezer and dough was made from it. Obviously, resorting to tactics like these are not something that one would relish doing, particularly in a commercial setting.
In terms of amount of IDY that might be used in your very high temperature environment, I think I would go with about 0.25%. That is just my best guess at the moment since I have never found myself having to make a dough at a room temperature that is approaching 100 degrees F. Hopefully you next batch of dough will tell us if that value helps solve the problem.
EDIT (1/25/13): Since the link to the above Lehmann article is no longer operative, see the Wayback Machine link to the same article at http://web.archive.org/web/20070502014430/http://www.pmq.com/mag/2003spring/tom_lehmann.shtml