To Those Who Enjoyed Carkeet's I BEEN THERE BEFORE.

I also recommend NEVER THE TWAIN by Kirk Mitchell, 1987, Ace Books, NY;

From the cover:

Never the Twain
In which a young time traveler sets out to wreck Mark Twain's career . . .

"It was all very simple . . . well sort of.  All Howard Hart had to do
was go back in time and make sure that Mark Twain's literary career
fizzled out.

Why? Because Howard is the last living descendant of the obscure novelist
Bret Harte and he's convinced that with just a little help, Harte and not
Twain will become wealthy and respected.  And that would leave Howard
heir to literary immortality.

But along tthe way Howard encounters some problems.  The Civil War, the
Gold Rush, and a ravishing young lady of pleasure - to name a few. And
suddenly time traveling isn't what it used to be . . . and neither is
history."

This might be a bit harder to find in your library.  Try the used
paperback book stores in the science fiction section.

KJB