I'd double check numbers to see how much the tractor weighs. I was surprised by how much my old tractor, and the current one, weigh when I researched and added all the numbers up. Same with trailer(16' dual axle 1600lbs bare empty). Make sure to factor in all your gear, chains, fuel cans etc.
If I were to tow with the smaller truck, first thing would be spend the extra $ and put brakes on the second axle of the trailer too...
IMHO, towing at the rated limits is not bad. It is the combination of things like towing at the rated limts or over, and doing 70-80 mph etc. Just because you can tow at 70, 75mph does not mean you should.
Another thing... I found once I got a flatbed for the tractor, that is only a small tiny part of what the trailer gets used for. Since having it I have hauled cars, motorcycles, firewood, hay, pipe, lumber, canoes for Scout trip, towed it behind tractor with Cub Scout decorations/float, concrete block, wire panels etc, etc..... Might consider that in your choice of trailer, and how you use your truck or upgrade in the future...