In the old NADA guides the only terry close to your size was a 19' long unit (total length I assume)
and it was just under 3000 lbs, it did not say loaded or empty, but I would assume empty.
If you want something more specific, all you can do is
1 Weigh the unit to determine weights
2. Search for any stickers or stamps which may give hints to weights including alxes for their capacities.
What is your tow vehicle?
I wandered around a little looking at the weight you are looking at and will suggest that you look for an "egg" trailer. Scamp or a similar brand. They usually weigh 2000 or so empty, and are light enough for most vehicles to tow. And they are pretty high quality so if your willing to look at an older unit, one with no obvious water damage may be a safer bet than the old terry model.
