Give them a call, but in the past I've seen overnighters there. Mostly they pulled in under some kind of distressed situation, needing an emergency repair, and they could stay in their RV overnight. When you walk into the main doors, you're standing along a canopy and drive that goes to an electronic gate. Right there in that corner they have electric hook ups and (in the past) could have electricity. I've talked to several folks spending the night waiting on work to be done, usually available to do the work the next day. All I'm saying is, yes, in the past, they've allowed overnight parking. There is also a fairly large parking lot on top of the "hill" where RV's are parked also, usually coming and going. If not needed electric hook-ups, I think they put you there.
Good thing, down the road, if you don't mind a little walk, and across the highway, there's a McDonalds, and there's a gas-station / convenient store on that same intersection.
Go on the East side of I-65 and you can get diesel there at a truck stop style fuel station.
Next exit off of I-65 closer to Indianapolis (North of there), there's a Wall Mart.
Edit: If you're traveling on North up I-69 toward Fort Wayne, Indiana, I live about 2 miles from the Pendleton (Highway 38 and I-69 exit). I live in the country and can give you a nice paved driveway to park overnight. Also can give you a 30 amp line and water. It's dark out here, and sometime you can hear the coyotes howling! Give me a private PM if interested.
