Looking for diesel or gasser? 4.5t? Is that 4.5 thousand kg's or pounds, cuz it makes a big difference. Do you have the chance to test drive a truck while pulling trailer? Most of the 3/4 and 1 ton's come with a receiver but the trailer brake is an option (factory one is "built in"). From what I've learned is the 6.4L (diesel) is not very good on fuel as it has the problematic DPF and related issues. Always remember, the newer it is, the more warranty is left and some may even come with extended warranty. I can't remember what gas engines are in those years...I'm thinking a 5.4L V-8 and (?)6.8L V-10. Good luck with your hunt.
Oh, and welcome to the site.
The Hauler - '05 F-350 4x4 CC Dually 6.0 Powerstroke
The Project - '90 Ford Bronco 4x4
The wife's - '11 Ford Escape
For every minute you are away from work...you can add two minutes to your life!