Slides out at Wal-Mart is generally frowned upon but does seem to be the norm as most RV's these days are barely usable without at least some of them out. My RV can be used with the slides in but it means crawling over the master bed to get to the rear bath, so not ideal and I will put out 1 slide if I can find a safe, out of the way place to do it. Most try to do as stated above and park parallel to the outside or a planter that will allow the slide to not protrude into a lane, and others sometimes park side by side and open their slides toward each other to the inside of a row as not to have it protrude into a lane.