Penguin is usually fat, but the Gotham tv show pulled off a skinny version. Plus, Jonah has been losing weight, so he is somewhere in between the two body types.
My first choice for Hill would be Detective Bullock. I think he would knock it out of the park being a cop in a horrible city, doing a dangerous job, and watching some caped vigilante get all the praise and credit. I could totally see him ranting about how Batman is the cause of the problems, filled with resentment and frustration. But, if they aren't going that route and they really want to insist that he has to be the villain... Make him Clayface. An actor who has all the skills, but gets type-cast based on his appearance, so he ends up using the Clayface goop to further his career until it gets out of control. Hill could really hammer him home as a tragic character struggling with addiction, instead of just a giant pile of mud that can talk.
frank gave that show his all...he made the initial show a hit....gave all the actors and actresses who would play a batvillain later a masterclass on how to do it...fing legend...