Jumpit, I would work on getting her to lead and move forward on your cue into, around, over and through ANYTHING before starting a fight at the trailer. Go in and out of doorways. Ontop of and over tarps, bags, plywood, cement curbs, changes of surfaces. Work on leading her over things and work on sending her over things.

When you have a well established "Go forward where I ask, when I ask" then bring the trailer back into the equation.

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