That's going to limit you to a very basic 13'er and you'll still need to pack carefully. See the sticky thread Trailer Weights in the Real World
in the General Chat section for some good information about actual loaded-for-camping weights. Assuming you have a smaller tow vehicle, brakes
on the trailer are going to be essential, and not all of the smallest trailers have them.
You may want to broaden your search radius beyond Arizona. In general, the smallest eggs sell really fast if they're in good shape and fairly priced. I'd check Phoenix, Tucson, Albuquerque, Flagstaff, and Las Vegas Craigslist frequently, in addition to monitoring this site, eBay, and fiberglass-rv-4sale.com. Do you have a budget in mind?
Good luck in your hunt!