This is something you'll want to familiarize yourself with:
Persistence of peanut allergen on a table surfacehttp://www.aacijournal.com/content/pdf/1710-1492-9-7.pdf"Peanut allergen is very robust. Detectable Ara h 1
was present on a table surface for 110 days post
application. There did not appear to be any allergen
degradation over time. Variations in the Ara h 1
levels were likely due to variation of distribution of
the peanut butter on the table surface. Active
cleaning of the table surface appeared to be the only
way of removing the allergen. Even after 110 days,
cleaning the surface with a commercial cleaning wipe
removed the allergen immediately."
The Lysol and Clorox wipes (don't actually contain bleach) are effective and may make the cabin safe enough if peanut is not eaten there while you are there (or again).
I would wipe all surfaces you can--even the pantry shelves where PB has been--with them. Also consider the silverware drawer.
It may be that your kiddo is not that sensitive, but my child has had anaphylaxis twice from accidental ingestion at school (touching surfaces and later ingesting the protein picked up).
I do hope your family becomes understanding. It may take some time educating them. And our experience here is that some families become welcoming and some unfortunately do not.