The only places in California where I've seen restrictions on Walmart parking is in the higher tourist areas. For example the Walmart in Pismo Beach has signs prohibiting overnight RV parking. I do believe that was brought about by City ordinance. I live close to a Walmart that is on 99 which is a major North-South California freeway, and I see RV's in the parking lot every morning. But there's nothing else here to do other than stay overnight and get back on the road. But even with that, I have seen the same RV's using the lot for extended stays. That is what will ruin it for everybody.