Hi Shane -
When you say opting them in via blind forms what do you mean exactly? Like, if they engage your list rental provide will turn over the contact data to you? The best tools I've seen for this kind of list rental contact acquisition have involved dangling webinars in front of the audience being solicited. Then you've already got a built in reason to capture their contact information and don't have to rely on a blind form that won't capture them unless they are already known to your Eloqua instance.
Thanks,
LK