I've got to complain, campy is way-overused and misused by a lot of fans, some seem to think any and every comic relief scene is campy and may make the whole film pretty campy.
I think the best definition of camp is fairly simple but specific-overdone & excessive in a way that is self-mocking. The idea that it is failed seriousness seems at best an odd and dated and maybe snobby one, I guess I can see how it can come from naivety+exaggeration+seriousness but that seems a very rare combination and even more so to combine them intentionally. It's also not really entertaining, Plan 9 aside (although even there some of the actors probably did exaggerate intentionally). By that, B66 wasn't campy, it was a very intentional and non-naive spoofing of naivety and seriousness.
From my definition, there's an element of campiness in Bane but there also was in the Joker, that they're both so Black Hat-wearing, nearly mustache-twirling Evil and hypocritical (Bane a bit more in talking more to the public about it), claiming that he made the people free and that if they don't follow his orders he'll blow them up. Also maybe in that, at least in retrospect, it's pretty obvious that Catwoman would initially betray Batman and that highly-focused-on Miranda Tate will likely end up being twist evil.
I don't see how Bane's agenda, though murky, was particularly less clear than the Joker's, Joker's wasn't clear until the interrogation scene (halfway through) or, later on, the hospital scene.