Have you ever seen the Prana Stretch Zion shorts? I use them for nearly everything - they've got a cinch belt that works pretty great, but you can also remove that and they've got real belt loops. They're very rugged, stretchy, and dry quickly.
They're originally sold as climbing/hiking shorts but I've run rivers and surfed in them with no issues.
They're originally sold as climbing/hiking shorts but I've run rivers and surfed in them with no issues.