I'm amazed that you use manufacturer's dry weight for making such determinations.
Every single trailer I have ever seen figures on weighs significantly more than their stated dry weight when a transporter picks them up at the factory and hauls them to a dealer. If the manufacturer's dry weight is even intended to be somewhat accurate it does not include a battery or batteries(most have at least two now), LPG, air conditioner(s), larger tires and wheels, suspension upgrades, two television sets, washer/dryer combos, or a dozen other popular accessories.
Of what possible value is dry weight? Who is going to haul a recreational trailer empty and dry? Even if dry weight was accurate, which it is not, what good would a trailer be without LPG in the tanks, water in the fresh water tank, food, clothing, utensils, personal items, etc. ?
Here's a good example of dry weight that I ran across just today. My daughter and son-in-law bought a 24' enclosed race trailer from my grandson. It was manufactured by Forest River and has all sorts of fancy trim, lights, generator, work bench, etc. It was originally sold and registered in WV where my grandson lives.
Before it could be registered in TX it had to be weighed on a certified scale, inspected for lights, tires, brakes, etc. and VIN verified. My sil is a very busy man running a construction company so I agreed to help my daughter today get the trailer registered.
The WV title showed: Dry Weight 4200 lbs. GVWR 9900 lbs. I knew that was bogus because I was the one who pulled it here from WV last November. Today I pulled it on a certifed scale, unhooked and dropped it, and moved my truck off the scale.
The trailer axles weighed 4,180 lbs. which is what the mfr. claimed the whole trailer weighed. The tongue, also resting on the scale but a different section, weighed almost 1200 lbs. I forget what the exact number was. Total weight was about 5400 lbs. Clearly the manufacturer provided a bogus weight intentionally or weighed only the axles with the tongue supported by the tow vehicle. The so-called dry weight was off by approximately 28%!
I would NEVER use dry weight for any calculation regarding trailer weight. That will lead to some very inaccurate and potentially dangerous decisions.
The only useful weight is GVWR because a trailer, loaded for use, will weigh very close to GVWR. The best way to determine weight is to take it to a scale but that is very hard for a prospective buyer to do with a new trailer. Next best way to know what a trailer will weigh is to read the GVWR off the VIN tag.