So, they should have mannequins there. They would most likely look something like this:

https://www.pgmdressform.com/DRESS-FORMS-PGM-Professional-Dress-Form-USA-for-Fashion-Design (see Industrial Grade Dress Forms)

No heads and no feet. Possibly arms. Would come in multiple sizes, both men and women Not likely, though, to have anything in kid sizes, given that they make work clothes -- which would be a problem, unless you substituted just a half-body torso, which would probably work if you have all of the mannequins covered with sheets.

At any rate, it wouldn't fool the border patrol.