The problem with casting people from True Blood is that so few of them have given any indication of being able to act (which is a result of the writing, which basically contrives reasons for them to take their shirts off and glower at the camera, but not really
act, per se).
Then again Tyler Hoechlin from Teen Wolf is being considered for the role of Batman, and his only role on that show is taking off his shirt and glowering at the camera, so, maybe a Joe / Tyler flex-and-glower-off would be totally appropriate...
I'd totally cast Rutina (Tara) as Vixen and maybe Ryan (Jason) as Booster Gold, 'though. The Blood League? Naw, True Justice!