I'm kind of in the same boat as you. I normally do the "full" Horsey Hundred over Memorial Day weekend. Last year, that was 180 miles over two days. I felt great. Mr. Silver (from TE) even burned up the road on Sunday's ride.
This year, I've decided to do a shorter route on Saturday and to play Sunday by ear. I just haven't able to train as much between travel and bad weather. Plus, I haven't gotten the fit on my new bike quite right just yet. It's been kind of a bummer. I'm making progress, but it's been a bit of trial and error.
After responding to your post last night, I actually did a search on Mapquest to figure out how far away Tulsa is from Indianapolis! I think it was 640 odd miles. That's doable, right?
Be good and have a great ride!
Live with intention. Walk to the edge. Listen hard. Practice wellness. Play with abandon. Laugh. Choose with no regret. Continue to learn. Appreciate your friends. Do what you love. Live as if this is all there is.
--Mary Anne Radmacher