I would rather be at the very max with a 5th wheel than a TT any day.
As far as I am concerned bigger is not always better. Many great spots have length restrictions.
OK having said that start with your actual tow capacity including all options. Anything that reduces capacity must be considered. Your owner's manual or the towing guide will have this. Don't just look for the highest number, you need your number. Keep the trailer GVWR within this tow rating for best results. Look in the footnotes if there is any reduction due to frontal area of the trailer.
Next you need to prove out the weight carrying capacity to carry the pin weight, hitch weight, extra truck cargo weight. This may also reduce the size of the trailer.
You could weigh the truck and post the front and rear actual weights and post the actual trailer model you are considering for best answers.
Yes this is a bit tedious and frustrating. I don't think 10,000 is a magic number. And we don't know if that is dry weight, Gross weight, or something in the middle.