A couple of things I would look at. What is the pin weight of the trailer? You may need helper springs in the rear. How about the brakes on the truck and trailer? Are you still running drums all around? If your trailer brakes are fine, you would need to install a brake controller in the truck assuming the trailer brakes are electric.
I might worry about the 250 not having enough power to pull all of that. A 292 would be better
