Here is an old "Rule of Thumb" that I have used for decades, and it is still useful today with regard to towing capacities:

Multiply the engine CID by 30 to get the maximum GCVW (gross combined weight) if you are towing in mountainous terrain. If you are primarily towing on flat land, or have an F250 or above, then you can go to 35 times the CID of the engine. This assumes the use of a weight distributing hitch.

With your example, I would look at about 10,500# to 12,000# gross combined weight.

I hope this helps.