Shelf-stable "frosting" for a savory "gingerbread" house? My mom read a Rachel Ray magazine, and is planning a craft project with my nephews where they make a log cabin out of pretzel rods.  The problem is that it likely won't be eaten on the same day.

The magazine called for using spray cheese, which I would assume would have lots of preservatives, and she was thinking of using whipped cream cheese (until I raise the issue of storage).

Everything that I can think of to use (icing, caramel, melted chocolate) is relatively sweet.  Is there something that we could use that would be sticky, non-sweet and be safe after being stored at room temperature for a couple of days?  Given how it's being used, it won't be tightly wrapped.
Peanut butter might work. It is safe at room temperature and not really sweet. It is somewhat soft, but so is the canned cheese. Natural peanut butter with the oil poured off might be thicker for use as mortar. The flavor would be good with pretzels.