You could try Yhidra. She has a sacred site in Laos.
Hmmm...I'll have to check up on her.
The only write-up of Chaugner Faugn I remember was a particularly deadly pair of scenarios featuring him in Curse of the Cthonians, so he clearly hasn't been as overused as, say, "The King in Yellow" has lately!
Though while I fully understand where that perception of Yig as a SW US kind of thing comes from ("The Mound"), the "Father of Serpents" would presumably be found anywhere there were serpents, so there wouldn't be anything inherently wrong with using him in the Mekong, or the Namibian karoo for that matter! Either way though, I have to tell you I'm really looking forward to seeing this Yig campaign whereof you speak!
There is an excellent write up on Chaugnar Faugn in Horror's Heart the campaign set in Montreal.