They still make a 13'er, and that is probably as large as you'll want to go. A 16' Casita
typically weighs around 2400-2600 pounds loaded. A 13' Scamp
generally weighs 1500-1800 pounds loaded, more if it has a bathroom. Casitas tend to be a little heavier than a comparable Scamp
You might want to take a look at the Trailer Weights in the Real World
thread for some actual user data. Post #297 links to a useful spreadsheet of the data you can sort and filter. It even calculates stats (max, min, avg, std dev).