I wish the author would stop doing small scare and hit us with the real danger, it's pretty evident he's setting up something with the old van, with the details about the place and how the other door can't be opened.
Also, they should bury the leftover cash in someplace now that they have a few cards for their personal use, that's now the wisest move. Worst case scenario they get caught and they can't be killed because they don't give up the money, and they've traveled way too many places so nobody can know where they hide it for sure.
They have no reason to keep it close.