The thing about mold is that once one of the three things it needs to grow are eliminated, it won't be present. It needs the right humidity, the right temperature, and a source of "food". After that it becomes a matter of cleanup.
Those mold test kits measure for spore presence. A mold spore is so small and lightweight that one hundred will fit through a screen opening. It also takes around 24 hrs. for a spore dropped from ceiling height to fall to the floor. The test kits are very inaccurate.
As was posted, one of the best odor eliminators is an ozone generator. It would be best to tent the RV and let the generator run for some days. Beware that certain materials, notably plastics, can be harmed by ozone.
There are also fire recovery products that will mask odors and organic based odor eliminators that are applied like topical sprays.
Good luck with your smell issues.