Blue Water Grill
These restaurants are very accommodating to diners allergic to gluten. I've eaten at all of them with a friend who has celiac. Before ordering, just make sure your server understands that you (your teenager) has a gluten allergy. You would be surprised how knowledagle these little small town restaurants are.
I'm sure more restaurants are gluten-free-friendly but these are the ones I can personally vouch for. You will definately not go hungry!