Sorry , But I just do not get the whole Tom and Huck thing at SDC. The characters are river rats from a river town. In the past SDC has done a great job of stealing characters from other parts of the country and using them. Hatfields and McCoys are Kentucky/West Virginia. Tom and Huck are northern Missouri. I say use what you have and quit stealing others ideas.
I think the Twain thing is because of the time period and generalized location. The Adventures of Huckleberry Finn was published in the US in February 1885, smack dab in the middle of the decade that SDC represents, and since HF and TS are set in Missouri, I guess SDC figured it was close enough to be used as a theme. It'd be pretty easy to have the characters say that they're visiting the City from Hannibal; that's what the princesses at Disney do ("Hi, I'm Elsa. I'm visiting from the Kingdom of Arendelle" etc.)
But I do agree - it'd be best if SDC could create its own characters/use the characters its got and just go from there.
In fact, I had actually been outlining some kids books that I'm still hoping to write that took place at SDC/Marmaros and featured different SDC characters (for example, one book would be about Doc Harris, another would feature the Saloon characters, etc).