Fully loaded weights tend to be north of 3000# and tongue weights a little over 400#. Dry weights for 17’ deluxe models as spec’d by Casita are 2480# and 365# (before options).
You can find scaled, on-the-road weights of various makes and models in the thread “Trailer Weights in the Real World” in the General Chat section. Post #297 links to a handy spreadsheet. There are a number of Casita 17D’s in the database.
At least in all-molded fiberglass, most of the relatively few tandem axle
units currently offered wouldn’t quality as “ultralight”. The Escape
19 is the only one that just might qualify,. On the other hand, the Casita 17 is a very popular single axle