basically, what pinkbunny said. It's not that hard to make a simple gfcf meal--gf noodles with pasta sauce, give water instead of milk to her or ask her family to provide her favorite df milk. Meat and veggies, eggs, frozen gf waffles with syrup (no butter), etc. When you start looking at it really closely, you'll find that there are more gfcf foods out there than you might think. I'll be back later with a bigger list of "naturally" gfcf things.
I have NEVER heard of someone who has a gluten intolerance having a contact issue with playdough or anything else--the allergen warning on playdough is more geared at severely wheat allergic kids who DO have a contact issue. Trust me, I'm on several forums that have a large food allergic community, and a contact gluten issue has NEVER been mentioned. As for other art supplies, I've never heard of gfcf contact issues with those either.
I'm gluten free myself, and lactose intolerant up to a point. I'm well-versed in food allergies and intolerances.