I think the problem, in part, IS that the life is too well documented.  It
is also too chaotically diverse.

On this second point, the comparison to Henry James is pertinent.  Though
James's life presents complexity on complexity, Clemens's life presents
several magnitudes greater complexity.  Moral calculus can yield an equation
that equals James; one needs human chaos theory to approximate Clemens, and
that's before you bury him under Mark Twain.  With Clemens/Twain, any true
statement you could make based on strong evidence could be contradicted by
several other statements based on equally strong evidence.  Making sense out
of this variety would take more than 20 or 30 years; it would be an Odyssey
with no magical Phaecians to take your shipwrecked self home.

Gregg