Hello, i was wondering what the minimum size would be for driving a mini, my gelding was trained by a very reputable trainer to drive and i took lessons but at the time had nowhere to drive as i was boarding and nowhere to keep a cart etc i have since moved and my boys live with me now but not able to find a minimum space, i can lunge him in a gallop in the area i would be driving in, i just cant seem to find the answers im looking for online