Pittsburg, PA to Fayetteville, AR

We usually stay at the KOA's along that route. They are usually near the highway and convenient for overnight. www.koa.com
We've stayed in Greenfield IN (near Indianapolis) in Brookville OH (Dayton)
If you don't mind traveling a few miles off I-70, we loved Forrest W "Bo" Wood Corps of Engineers campground near Sullivan IL. exit 160 then north on Hwy 32. Find info on www.recreation.gov
Just west of St Louis, we stayed at the KOA in Eureka.
If you have time, stop in Springfield MO and visit the Fantastic Caverns. You ride through in a jeep. There is a KOA in Springfield MO but it has train noise if that bothers you.

I've used a KOA east of Indianapolis that was OK. Beyond that, my preferred routes into the Missouri-Oklahoma-Kansas corner take me through Springfield (Illinois) and Hannibal, so as to avoid St Louis, so I know what is on US-36 and US-54, not what is on I-44.

Before getting the RV I traveled I-44 through Missouri several times a year for about 20 years, so I know that RV parks are easy to find along that route, but have no experience to make a recommendation until the Joplin-Carthage area (where I can recommend Coachlight RV Resort). That's beyond your destination.

Missouri and Illinois state park campgrounds will not usually have full hookups. I've been in Illinois state parks that did not have water at RV sites, electricity only. In those states, for full hookups you will be looking for commercial RV parks, not campgrounds.

Can't tell you about Indiana state parks, as they charge a fee to get in the gate, so I don't go in them to check them out when passing through. My travel seldom takes me into Ohio, I go into Michigan on the west side of the state usually.