Nah I'm thinking grizzled veteran who has to be killed. Starte boss in this scenario. A Vix update may be pretty be to begins with (as Tinkerer said, that's why she was also left out of the poll). I feel a Vix update would focus soley on her & no other/new women. Could open a path to someone new somewhere along the lines.
But I'm a fan of killing off a boss Slayer then faking a Dragon slaying for the reward & to divert attention. Like from the film Dragon Heart. If you have seen it you know what I mean lol.
Well we could also go with the basic princess in distress story, if let's say a princess visits the temple after hearing about the MCs feasts and asks him for help, as she is supposed to mary an older and fat guy in grey fort.
You convince Vixxenatrix to attack the caravan at the western crossroad and than "save the princess" from the "monster"... your reward could be the girl, afterall you are already the mayor of Weirdwood and have a pretty good economy (thanks to your drug deals with the Elves), so maybe her financially strained dad would hope to forge an alliance with you.
For Vixxenatirxs reward she could hand the MC a treasure map from her stack and order him to recover it in order to build a nest for the kids.
Adding Tinkerers Humor in it the plan could even fail as the Caravan is being attacked by bandits before Vixxenatrix appears and she than saves the princess by killing the attackers