My left hand has very limited use. A brace helps me have more use of it. I cannot use a full sized lunge whip. I use the short lunge whip offered by SmartPak. When I have bad days, I do not have the ability to use a whip. At first, I would have a whip person, but I have since taught my horses voice commands. They actually now “up the pace” when I say “MORE” or cluck. I generally prefer to say more, as a cluck often leads to too much forward.
For long lining and ground driving, my horses are “light” enough that they do not yank or pull, so I hold my lines like reins. There are times when I drop my left line, but I tell my horses to stand and they stop immediately. They did not become good overnight. They learned voice commands first on the lead line and slowly, but surely I was able to use the commands in a round pen on the lunge and with long lines. I am now able to lunge, long line, and ground drive in my entire arena because my horses compensate for my disabilities.
If you have any more questions, feel free to pm me. I am more than happy to help where I can!