If she really had to go and that was it why would you go far off the trail at all. How busy would the trail have been for necessary modesty? You wouldn’t want to do your business on the trail itself but anything beyond a short distance would be overkill no? I am not an expert on hiking but for those who are is there a standard procedure for a bathroom relief break?
I walked that portion of the AT back in the early 80’s...most lean-tos had a ‘bathroom’, so to speak. You sat down on the crossbeam, and added to the pile. Some even had a roll of toilet paper on a nearby tree branch. Easy peasy. Of course, if you’re squeamish...