Something doesn't seem to compute. If you are using 1/8 cup of IDY, that is 6 teaspoons, or 0.6375 ounces by weight. Fifty pounds of flour is 800 ounces (50 x 16 = 800). So, from a baker's percent standpoint, your usage of IDY is 0.6375/800 = 0.0007968, or 0.07968%. I don't know what kind of pizza you are making but 0.07968% IDY isn't going to support much fermentation, and certainly not in a cooler. Am I missing something here?
Are you making two different types of pizzas? If you are using 15 ounces of dough to make a 12" pizza, I calculate a thickness factor of 15/(3.14159 x 6 x 6 ) = 0.1326292. If you are using 21 ounces of dough to make a 16" pizza, I calculate a thickness factor of 21/(3.14159 x 8 x 8) = 0.1044455. That's a big difference. Either way, are you having problems with both crust thicknesses?