We used to do the same type of thing at a range club I was a member at in PA. Except we used an electric motor I rigged up with a remote switch. Had a guy go over to send it back since it was an older motor and more of a pain in the rear to set up a reverse polarity to send it back than it was just to have someone shoot over and send it. Just rigged a 100 foot extension cord into the circuit with a simple on/off switch at one end. Easy peasy. Little old motor would cost you around 20-30 bucks and I'm sure you have an old drop cord laying around. Just a simple on/off household switch and a box would be around 6 bucks max. Be much safer for you guys.