Thirty years ago, when I use to take my folks small toyota dolphin motorhome on scuba diving trips down to Santa Cruz, I would simply drive through the neighborhoods at around 10pm at night until I found a quiet dark set of homes and just park curbside, then quietly and using my flashlight, jump into bed and go to sleep. I had my alarm clock set at 5am and with a couple of minutes of waking up I was back on the road. I was very covert, sneaky, and quiet. Nobody ever bothered me and I left nothing behind.
Lately I have read some articles about the homeless and that some mental health workers are encouraging some people with mental health problems to live in a small rv. I think the problem there is 1) not covert, but simply happy to park in a spot until run off, 2) many of them dump right on the main streets (as reported), 3) and some making drugs in their rvs (as reported). None of this bodes well as cities are encouraged by homeowners and business owners to restrict RVs to respond to those behaviors.
Yet, it seems that being very inconspicuous, getting heads up permission, not treating the spot as a campground, and staying in RVs that are well maintained, don't look that old, and don't look broken helps to avoid some of the attention that shorter, older, and poorly maintained units get that the homeless favored and get attention from the locals and the police.
So, don't look or behave like you need a visit from the police is another thought. I kind of doubt this applies to any member.
Maybe a letter of appreciation to your local Walmart after your stay with receipts of your purchases would be another way to keep the WM management constantly happy letting RVers stay.