Family doing 3 month summer trip, Class C or Travel Trailer?

Kind of late to get started this year isnt it? Yea a TT is probably your best option. Check out used full sized vans. Not the extended ones, but a standard passanger van. Most have decent towing ability.
Small kids can sleep about anywhere, so start searching the used market. There should be many decent ones available in your area. Keep the size short, under 25 feet, and you will have better camp site selections.