I don't find it credible to explain the physical evidence in the RV. I also have no evidence that children ever played there.
Further you have on these threads heard from mothers of children and such who have stated that kids do play in RV's parked in the neighborhood. An RV is like a "attractive nuisance" in that way.
To ignore common sense in order to arrive at guilt is not presumption of innocence. And that is what you are doing.