I just found this thread in the New Posts feed.
Your route from Xenia to Greensburg is fairly flat but not very interesting. Lots of corn and soybean fields, with occasional small wood lots.
It's 125 miles, 2700 feet. Just 21 feet per mile.
I drew an alternate route. It's more interesting to ride, but hillier.
120 miles, 4300 feet. 35 feet per mile, not bad. But there's some steeper grades along the way. I don't think I would route this way for loaded touring, but it could be quite nice for light weight credit card touring.
It's 6 miles of a slight downhill grade on the Little Miami Trail out of Xenia, just enough to notice. And 5 miles downhill at mile 72, with maybe a 1% downhill on that bottom half, soft pedal it.
Most of western Indiana that I've ridden has extremely low traffic away from the main highways, which can be busy and annoying. Some roads are chip-seal, a thin tar layer with gravel embedded. It can be annoying to ride when it's fairly new, but it does wear down a bit smoother. Indiana counties seem to chip-seal roads at random--some are smooth asphalt, some are older smoother chip-seal, some are new and buzzy.
The purple sections are roads where I'm somewhat familiar with the area, but didn't always know which road to choose from the alternatives--could use a little more research.
The green line is the river road to Brookville, very scenic and quiet, but rough pavement on part of it. Tires that work on the GAP trail will help, but it works with road bike tires.
https://ridewithgps.com/routes/32776803
It might not fit your time and distance schedule.