Sounds to me like your Montana might top out at around 13,000 pounds, or more. With a loaded pin weight of around 2400 pounds or so. You are correct in that your truck needs to be a later year model and (minimum) a 1 ton (350/3500). A dually is not needed. And that trailer could use a strong motor in your TV. A V10, or a diesel. Or a late model large V8. Forget the earlier and smaller gas V8 engines.
If considering a 09 and down model year, the only Ford choice is the V10 gas engine. Forget the Ford diesels, and smaller V8's in those years. Not good for your needs. Look at the Ram diesels, or the GMC/Chevy Duramax Diesels. Or maybe a larger gas engine. Be sure to get a truck with a 5 speed transmission. A six speed is even better. Forget the four speed transmission models. Pay attention to your rear axle ratio...depending on the engine choice. A less powerful engine needs higher numerical rear axle ratio.
A short bed has some advantages. And if your trailer has sculpted corners, no slider is needed. With a small child, I would not recommend an extended cab. Go for the full CREW cab. A whole lot more convenient for you. If you get the crew cab with 8 foot bed, that is a long truck. And maneuverability goes down.
And yes...you did it right by buying the trailer first. Now you know what you'll be towing. And can size/option your truck appropriately. Will help you to bring along someone that can help you determine the right truck.
Best of luck.
