It's been a long time since I've checked in here, but my two little guys are basically driving now. I mostly just ground drive them because I feel they're still a bit young for any kind of load for any length of time, but I have put them on the cart for a few minutes at a time, on flat hard ground just because I couldn't contain the excitement to see how they'd react and they're awesome, not a single issue, took to it like old pros, don't even seem bothered by the little bit of weight. I'm sure when we're ready to start seriously pulling they'll be little troopers and it will be onwards and upwards from there.
As for our ground driving we've been walking the roads and this weekend we were faced with a lot of different traffic. Trucks loaded down shipping cattle, huge hay loads that took up the entire road, rickety hay rakes being hauled home behind old farm trucks, lawn mowers, barking dogs, people walking on the road, trucks stopping to say hello, etc. Plus while I was working my my spookier horse, we had a parade of ATV's one of which was hauling a hay wagon full of screaming kids. He was awesome, just flicked his ears at them and kept on walking while the convoy passed us. I was totally impressed with my little guys, they're doing awesome.