Is there any way to draw named vampires out of thier castle prior to the final assault? I am at a point now that I could take Harkon down in a one on one. But that is not in the script. But I was wondering if any of his minions could be enticed to come out and play with me awhile so that I can destroy them before the Dawnguard attack begins in earnest. Any ideas?

Not exactly sure, but it seems the quest will not go further w/o the DG's help. I never went Castle Volkihar w/o the DG, thus unsure.

Nope. they won't come out and you can't get in.

Oh well, I'll just have to exploit some extea followers!