I strongly second the toilet paper idea, as long as she remembers to change frequently. Or, just have her wear multiple, regular panties.
Also, what about paper towels or art paper rolls ? The smooth, thin and soft kind ? I am thinking of those cheap brown rolls that might not irritate / aggravate her sensory issues. A 200 ft long art paper roll retails for under $20.
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O villain, villain, smiling, damnèd villain!
My tables—meet it is I set it down
That one may smile, and smile, and be a villain.
At least I'm sure it may be so in "Denmark".
-- Hamlet, 1.5.113-116