Most of your statement, I agree with. Except this. A 10k trailer is generally built quite a bit heavier built than a 7k. He’s going to be pushing his tow limits, if the trailer is too overbuilt. It’s also going to add a lot of cost, for very little potential benefit IN THE OP’s SITUATION. I capitalized that part because, usually, I would
agree on this part, too.
If you Google 7K trailer, you will read lots of reasons to buy a 10K, from guys who have bought 7K.
Better springs, better wheel bearings (bigger) ,better brake drums (bigger), better tires (bigger), etc.
4 years ago, my 14K x 20' equipment trailer cost $4,400 OTD, and it weighs 3,300 lbs. It would likely be $800+ more today.
As an average I would assume a 1O,000 lb x 18' trailer would weigh somewhat under 2,800 lbs.
Kaufman trailers in North Carolina, is a major trailer builder. They would be a good source for weight/cost information.
I have seen Kaufman trailers on highways throughout the USA
They will deliver to you anywhere in the USA if need be.
I did not buy my trailer from them,.... but probably should have!
In my opinion, to save a few bucks on desired initial trailer expense, is almost always false economy!