Can't help with your specific situation, but the Walmarts east of there have almost all become no RV/camper parking, except between the hours of 23:00 and 06:00. No parking there all day any more.
We first noticed the RV parking restrictions in other areas that used to allow it, and then noticed last Fall that the Walmarts were following the trend away from becoming 24 hour free campgrounds. Over the last decade we've traveled out to the Gaspe and the Maritimes many times in summer, and it was really getting ridiculous some of what we saw going on in public places, like lawn chairs under awnings, BBQ grills, picnic tables, and even a portable propane firepit in one Walmart along the St. Lawrence. Might have been Riviere de Loup or Rimouski or Matane, can't recall exactly.
They restricted the roadside pullouts along Rte 132 a few years back when they started turning into free campgrounds, as well.
We had pretty much seen the writing on the wall years ago, for similar reasons. Funny part was, it was mostly campers driving or hauling RVs with Quebec plates that really abused the daytime/overnight parking situation. They've not only screwed themselves, but everyone else, too.