Sounds awesome SKIP
. I have a few ideas for how the story would come together. I would do the Roman Sionis and Matt Hagen origin together, where they both grew up in the same neighborhood so Hagen was involved with the Sionis family because of the childhood friendship.
Overtime Sionis would be ready to claim his family fortune and take the head of the crime org from his father, but Hagen, a struggling actor who was involved in a tragic car accident severely disfiguring his face, would ask for a loan from his childhood friend to purchase this experimental clay product that could regenerate his face. It would turn out to be temporary, and, when Hagen couldn't pay the loan, Sionis' father would force his son to "take care of the situation" or he would never get the reigns to the kingdom. Then Sionis, donning the black skull mask, to stop Hagen from seeing his face, would turn on his friend and drown him in the clay product, leaving him for dead.
From there, Hagen would transform into Clayface, and he would begin to kill all those who killed him, before discovering that the guy in the "Black Mask" was his friend Roman Sionis.
During this time, you could have Red Hood picking off random thugs and trying to take down the Sionis family "permanently", while Batman has to stop him and Clayface. There could be clever ways to tie everyone into the story together, but I think my Clayface/Black Mask tie-in would work well.