my girls small only like 5'3 and 110 lbs, first time she had 1/4 of a pill every hour for 4 hours, and was completely overwhelmed by it for 6 hours, she needed to sit down for the first 2-3 hours, second time she did the same and only needed to sit for an hour or so.
last weekend she thought she could handle it a bit better, so she had 1/2 and an hour later another 1/2, and she was completely gone, in a good way, but gone. overall i know she loved it and who doesnt but i think its better to be capable of walking/dancing and able to enjoy the festivals more, so i would advise you and your girl to go easy