The best place we stayed at on one trip was a BASS PRO SHOP parking lot (Central ALABAMA North of Montgomery I think it was). If you have ever been to one you would be aware of their OUTDOOR SCENE setups every place they can do it.
The area where they allowed over-night parking for campers was setup the same. This place even had a 20AMP service receptacle. Each area was separated with high shrubs.. Actually better than some camp grounds we have been too hehe...
We ate a big breakfast inside the next morning and bought a few things as well.
I would never plan on staying more than one night. This allows others to use the parking area on their transit journey.
We too always ask for permission first to camp.
Roy ken