Welcome, Hildur!
Sounds like your budget is modest, which will make finding a clean, ready-to-camp unit with a bathroom challenging. Decent ones typically run closer to $10K or more.
Challenging, but not impossible, and there's always a non-bath unit (which feels more spacious) and a porta-potty. Scamps have a compartment under the front bench designed to store a small porta-potty.
Have you verified that your vehicle can pull a trailer of this size? Scamps and other 13'ers weigh 1400-2000 pounds with options and gear. Bathroom models tend to be on the heavier side. Definitely read everything your owner's manual says about towing. It may call for
brakes on a trailer over 1000 pounds, for example. Not all 13'ers have them.
I love your retirement plan, and I'm sure if you're patient, the right one will come along. Best wishes on your "egg hunt"!