Yeah, I'd be all over the idea of Matty McConaughaughaninnynaynay as Dent. Halfway between Tommy Lee and Aaron with the approach, grounded like Eckhart but this ruthless extroverted hellraiser like Jones. And of course show plenty of the other side, the guy able to have a cogent & reasoned conversation with Bruce when his mind happens to be in normal-guy mode.
Sorta liking the idea of an older actor for it too, if it's the "he's already scarred and his mind's snapped" approach, too. He used to be the whole White Knight thing and was maybe a family friend, he knew Mom & Dad Wayne well, and Bruce since he was a kid.
While having no idea Bruce is Batman, interacting with them both separately. And he & Penguin really butting heads bigtime.