Since the OP is new here I think it behooves the rest of us ("behooves" is my word of the day) to go a bit easy on him. Full disclosure: I'm one of the worst offenders when it comes to mocking the whole concept of "Asphaulting" at Walmart.
That said, I can't imagine that Shrill Haters like me would notice or care about the difference made by an overnighting RV with slides in or out. As suggested, park by the trees (but don't Schitte in the gardens).
If the OP were to tell us where he's thinking of going, there's bound to be someone on this boondocking thread who knows of a nice place to pull over and overnight. For starters, many state parks offer the option of "en route" parking for a small fee. Yes, you're still overnighting in a parking lot, but it's in a park and presumably that's what you bought the RV for, not for impressing the shameless, lifeless freeloaders at Walmart.
Oops, I really tried here.