For the meatloaf idea, since they're just limiting gluten, not allergic, I'd still make it with traditional oats. Oats are NOT gluten, however, oats are almost always cross contaminated with gluten therefore they are off limits (unless specifically labelled gluten free) for those with allergies.
I would add a soup for sure for one of the meals a month. You could easily rotate a variety and they're easy. Chicken veggie. Tortilla. Chili. Meatball. Etc.
A variety of saucy meat and veggie dishes served over rice. We do a lot of things like that. Chicken teriyaki is a fave.
Tacos are another easy one. Just go with corn shells instead of flour for no gluten. You can get the hard or soft corn shells -- whatever they prefer.
I LOVE the idea that you brought along some fruit on the side. Fruit is a life saver when you're exhausted but still need to feed littles.
Especially those cuties -- easy for kids to get themselves. Any berries, grapes, apples, etc. are fantastic too!