I have not tried leaving out the milk but I think you should be able to do so. The most recent Pizza Hut U.S. ingredients document that I am aware of is the one at http://web.archive.org/web/20100602083641/http://www.pizzahut.com/Files/PDF/PIZZA%20HUT%20INGREDIENT%20STATEMENTS%20September%202008.pdf
. That document shows the use of whey in the pan dough. Previously, Pizza Hut used a dairy blend comprising nonfat milk, whey and buttermilk powder. Whey is very hight in lactose, so you perhaps want to avoid using whey in your dough if it is lactose intolerance that your are concerned with. Whey is often added to a dough to get increased crust coloration. In your case you could increase the amount of sugar, or possibly you could add some honey to the dough because it has natural sugars that are more readily available for the yeast to use as food and to help increase the residual sugars to produce more crust coloration.
As I have mentioned before, in the U.S., Pizza Hut has gone to frozen dough in its stores, including the pan dough. And while I could not find any Pizza Hut documents showing what is in their current U.S. pan dough, I did find a Canadian Pizza Hut document that shows that PH is no longer using milk products in its Canadian frozen pan dough (it is still using whey in its fresh dough however). That document is at http://www.pizzahut.ca/Fileupload/ingredients.pdf.
That document is dated August 2010, so it is possible that the same pan dough formulation is being used in the U.S. Pizza Hut has become less revealing of its dough ingredients in recent years so we can't know for sure what it is doing in the U.S. anymore. Even the above 2008 PH pdf document is no longer available. I had to go to the Wayback Machine to find an archived copy (the one referenced above).
In your case, I am not sure that you will need to increase the formula hydration. Since nonfat dry milk powder will absorb some of the formula water, just leaving it out will increase the effective hydration.
If you decide to proceed along the above lines, I hope you will let us know how things work out.