Walmart
If on the road, a good thing, a Walmart may be available to you. Sam Walton, an avid camper, had extended an out reached hand to his fellow enthusists. A lot of Walmarts allow over night stays on their property, "boondocking", along with security checks from the store, cozy and cool. There are some stores that can not offer the over nights due to local camping parks petitioning against the policy, everyone needs to make money, what a shame.
Pilot - Flying J
These are great. They offer many amenities for the weary traveler. Many have dumpsites, and propane at reasonable pricing, especially with a members card, plus food, restrooms, laundry facilities, store, water, and secure boondocking. I have stayed at one for a couple of days. Don't know if that is acceptable but I wasn't bothered.
www.pilottravelcenters.com