A few thoughts on routes to Indy:
The Tulsa to St. Louis alternative would involve never-ending short, steep hills from about Joplin, MO to St. Louis. The one sane way to cross Missouri is via the Katy Trail, a great railtrail that runs west from Clinton to St. Charles (near St. Louis). The web has lots of info on the Katy Trail.
I'ed ride north from Pilot Point, through OK, to about mid-Kansas, then angle northeast to Clinton. With a slight detour to the west, you could follow an historic route by taking US-81 through OKL and KS. That highway follows the Chislom Trail route the cattle herds took to Abline, KS.
From St. Louis, angling northeast across Illinois would avoid the very hilly part of Southern IL. Once into the flatlands of IL, you'ed have clear sailing to Indianapolis.