Best of success hunting for a new truck and trailer. There is some really nice toys available for you to choose!
I'd guess a F-450 can tow virtually any 5th wheel you buy. Safely and comfortably. They can be serviced by any Ford dealer or automotive repair facility, except for the commercial tires and the need for a larger frame machine and alignment rack if/when needed. And although not exactly small, it makes for a manageable daily driver, except for cities.
I have no personal experience with larger trucks. Logic tells me they will be way capable. I'd inquire about the comfort for both passengers and trailer. As for availability and cost of service? I suspect big wallet my be a prerequisite.
Check with your insurance company, bank, and maybe even motor vehicles before buying. Some folks have found themselves forced into commercial status and the associated costs. I'd guess the Frieghtliner will be more of an issue than the F-450. Oh, and for these purposes, a F-450 Super Duty may be less of an issue than a F-450 cab and chassis.