The same difficulty of anonymity arises with the RV itself, a very ostentatious vehicle that not only can be traced with ease, it can be tracked retroactively on virtually every street, every highway, etc.
Regardless, for all we know the person isn't concerned with being caught (and may currently be deceased given that possible human remains have been found).
No need to publicly tip your hand. Just follow that trail of evidence, then use parallel construction to produce a different trail that you reveal publicly.
Regardless, for all we know the person isn't concerned with being caught (and may currently be deceased given that possible human remains have been found).