Need input on hiding sub from anyone (females especially)

Hi all,
I have a question.

I'm going to a place that does both the physical and drug screening.
Can they make you strip down completely for the UA? (Take your bra and undies off)
If no, can they make you lift your gown to expose your under clothes?
I'm a pretty hefty gal so I can either hide it under a breast or crotch it.
I have practiced both methods and can keep the temp without a problem.
I'm just really concerned about a sneak peek if you will.
I'm pretty positive they can not do such a thing, I just need some reassurance.
I've subbed once before and did just fine with it, but I never had a physical along with it when I did it.

Thanks in advance! You guys and gals are the greatest!!