For me, small floats weighted to barely float solve the swallowed-bait problem because I can usually set the hook the moment the fish first sucks the bait. (The bobber doesn't resist, so what we call a "nibble" with a big bobber becomes what the fish intended--a meal taken into the mouth.)

But if the problem is that the girl can't help looking everywhere except at the float, enjoying the company and nature (which is great), then the non-resisting float will probably result in gut hooking.

I don't have experience with circle hooks for sunfish. Long-shank hooks and #8 Kahle hooks (by Eagle Claw) don't always prevent swallowing, but at least tend to make unhooking easier. Reducing the hook barb to the smallest needed to hold the bait on also helps.

If you get on a really hot bite while she's along, try the mini floats. Could be if she knows the float will go down soon after it hits the water, she'll stay focused on it, and with successful hooking will lose the frustration some kids experience because they guess wrong so often about when it's time to set the hook with a big bobber.