It would seem like they could make a racetrack/LeMans type racing or snaking path in the Festhaus lot instead of a Christmas Tree stroll. Possibly even circling through Oktoberfest or down the Drachen Fire side. The obvious problem with the latter being people, foot traffic, and safety issues. Carowinds has their sleigh ride through the unpopulated and closed water park section. I'd say use the closed parts of the park at BGW, too. But hills, bridges and height restrictions would be problematic.
IF a carriage could fit through Festa and IF they decorated it as normal, there would be much more to see there than in the Festhaus lot. You could load at Marco Polo and maybe make it up that hill and over the Festa bridge? The space might be too tight at the tree for a turn onto the bridge. Any place would require an area large enough to turn or circle a horse and carriage around. Unfortunately, I don't think there is enough room to navigate successfully for this idea. Also concerned an incline of aggregate could be a tough surface for a horse to safely get traction and pull weight?