There are MANY people who cart with Rottweilers and other carting breeds (including my own Bernese). In my opinion it is CRUELTY to NOT work a working dog breed whether that form of work is herding, hauling or hunting.
Here's a couple of plans: http://www.make-and-build-dog-stuff.com/dog-carting.html
http://www.sonic.net/~cdlcruz/carting/pvccart.htm
http://www.wilczekwoodworks.com/wagons.php
I'm trying to find the plan for the cart being made for me out of a garden cart.
You should also google "dog sulky" -- I saw a Rott up in Canada doing this and he was AMAZING!
http://images.google.com/images?q=Dog+Sulky&oe=utf-8&rls=org.mozilla:en-US:official&client=firefox-a&um=1&ie=UTF-8&ei=NF-MS_nlG4f8sQOe3cm8Aw&sa=X&oi=image_result_group&ct=title&resnum=4&ved=0CCcQsAQwAw I SOoooooo want to do this with a pair of Bernese!
Papaw - relegating dogs to couch potato status simply because society as a whole has become a bunch of bunnyhuggers is wrong.
Saying someone is an "abuser" because they want to work with their dog is wrong and short sighted.