From my personal park data base...
My top choices for parking.
Flying J generally has the best parking setup for vans/ Pilot is smaller but both are generally van friendly. Some will limit parking or have no overnight parking.
Walmart actually is my favorite place to stay, and always my go to place after a delivery.
Just be aware that more and more walmarts have no overnight parking. Watch for signs. A good rule of thumb is if the WalMart is connected to other businesses, like a strip mall, they probably do not allow overnight parking. There are Apps/websites sights for finding walmart parking.
Also, if you see several motor homes or semi trucks you will probably be safe (but no guarantee).
TA travel center- Some TA's can be good, just not a place I seek out.
Loves- There isn't much love at loves for van parking. Some people have been able to, in a pinch I sure would try. But generally they don't want you there. And other then using their restrooms, I avoid them like the plague.
Most importantly, please follow what Ragman said