Just for clarification, with molded fiberglass manufacturers, models designated as 13' have a nominal 10' cabin, and models designated 16' have a nominal 13' cabin. So, I presume you're looking for something in the 13'-16' range?
It would be also helpful to have some idea of what condition is acceptable (ranging from like-new to needs-a-complete-rebuild), what equipment you require, a budget range, and a weight
limit (based on your vehicle's towing capacity).
Best wishes in your search!