Personally I would just slap templates onto the Bodak Skulk and then double check the hp and defenses to make sure they add up right for a solo (they often don't, or at least the hp doesn't, when you double up on templates)

Templates that might be best.
Cleric
Death Master
Death Knight
Shadowborn Stalker

Personally, I think that Cleric might be getting too complex since it would now have cleric powers. Death Master + Death Knight would make this thing mean, especially if it had a couple of normal undead with it (yes, I know its a solo, but despite the name solos don't have to be the only monster in the fight)