Hi Janice, I did an article on ground driving which I think Judy has on her website. It goes through step by step so it is easy for horse and person. I would not recommend driving from a bit because the lines put so much weight on the bit and tend to encourage the overbend as in the photo from your friend's horse. We generally use a nylon halter but you could use a sidepull.
We ground drive all our young horses and older horses as well. We have people drive each other and / or a chair to get used to the feel of the lines and how much pressure there is from the lines the further back you get. Robyn Icelandic Horse Farm Robyn Hood & Phil Pretty Vernon BC Canada www.icefarm.com
