Bought a 2015 Keystone Montana Mountaineer 356TBF this week from camping world Myrtle Beach,SC. I currently have a 2013 F250 6.7l diesel with Firestone airbags and a B&W Companion 20k hitch (non slide...
You may need to adjust the trailer brakes, as the new ones should be adjusted after just several hundred miles of towing. It was towed from the factory to the dealer. Did the dealer adjust them before you picked it up?
The 250 should brake just as well as the 350. You should have 2500+ pounds of hitch wt available, before reaching your rawr.