You are a skilled rider and have experience in training green horse and have the facilities and tack for such a job including a properly fitting saddle and the horse has been vet checked for pain issues.
You are in good physical condition and accept the risk for a major accident where you are hurt and have insurance to cover all medical bills for yourself and the horse.
You have professional help from an experienced equine trainer.
You are over 18 and accept legal responsibility for your mistakes.
With all the about checked off.....
Pony the horse with all tack on the horse for about a week over all kinds of terrain.
Use a skilled and trained horse to accomplish the task.
Pay attention to the overall conditioning of the horse.