Keep it simple for starters.
Payload is always the determining factor with half-ton trucks.
Look for the GVWR of trailer, usually stamped on driver's side front of trailer. Take 12 - 15% of this weight as trailers tounge weight.
Now go to the door sticker on truck and find payload CCC.
Deduct the trailers tounge weight, all passengers weight and cargo that you plan to carry on truck from the trucks rated payload and see where you stand.
If you plan to upgrade trailer in future like so many do then it would be prudent to look at 2500 - 250 series trucks.