We went to Wyoming last summer to get out of the Texas heat and choose not to stay in Walmart's along the way for personal reasons. Walmart doesn't do anything unless it benefits them economically.
Not withstanding that I wouldn't because of the etiquette involved, and yes the only reasons anyone in my opinion would stop would be for economics and convenience.
I want to be able to have the comforts the trailer affords when it is setup, stability, A/C, water, space and so on.
One thing we have had great success with are city or county parks many towns have hookups in a local park. Most are nice with hookups for at least water and electric. I've paid $40 for a KOA that turned out to be a dump and then $10.00 for a city park that was great, and the gas for the gen would have been about $10 for boondocking.
Allstays and RVParkreviews are your friend.