Plot hole: While it fits his style, the Joker's larger scale plans rely on a sequence of events that are largely out of his control and depend on an extremely precise sequence of events, timing, and luck, such as Harvey Dent or Rachel being saved (Dent remaining alive in the shootout, the Joker being caught, the police reacting in specific ways, a way to cover his escape). The hospital sequence likewise requires no one discovering planted explosives ahead of time, and him sneaking in prior to evacuation.
Suggested correction: Although your logic is solid, the Joker is a master opportunist and can change his plots midway to fit his needs. Had Harvey died, he may have targeted Commissioner Gordon or the Mayor as a replacement. We learned the Joker wanted to be caught so he could get to the financial planner for the mob bosses. As for the hospital, he may have simply removed his makeup like he did when he disguised himself as a police officer earlier and worn a surgical mask to cover his scars.
