Welcome
I think a well organized and prepared cult could take a warden out. I’m not familiar with the bayou but it can present some difficult terrain and if they know the area better than the warden, it could be used to trap or kill him. Water grounds out magic so if their hideout it surrounded by water, they could get the upper hand. This also allows you to present some problems/compels on your magic using warden pc. Also, I’m not sure water affects outsiders in the same way so having an enemy Weilding outsider sponsored magic would present a great challenge.
Also, instead of redneck werewolves, why not redneck were-alligators? They would be an asset because of their ability to navigate the waters.
I like the idea of the leader, the barbed wire saint, being possessed or weilding the magic of the outsider.