French Winch?
 

SO I get a Quebec Hunting/Fishing Mag at the office... In there, they have several PORTABLE winches based on Chainsaws.... These are designed for moving BIG GAME or logs, etc. pretty powerful.. Thinking.. HMM.. This could be adapted easily..

www.tmp-treuil.com
www.portablewinch.com
www.lewiswinch.com

Looks like they are geared for slower / more powerful pulling.. but... there's an idea here!!