I'm sure boar goats can do it since they are fairly big. I have no clue how to train a goat. I have done dogs and horses, but no goats yet. I would start by having the near the wagon, watching the wagon move, being up where they will be pulling it (but not attached0. Then I would attach part of the harness, and have one person pulling the cart behind the goat, and another person walking the goat. Then attach the cart to the goat. I would suggest having someone push the cart so the goat can gradually get used to the weight. This is just what I would do, but have no experience what-so-ever here so... hope this helps, let us know what happens.