Well we did it- we went off leash tonight for our first time. With how we've been progressing with our header getting farther and farther away, Louie almost didn't even notice that he wasn't there when we took the line off.
We worked mostly in the outdoor arena, testing Louie with the wind, hard bumpy sand, walking, trotting, trotting off the rail and around obstacles, and taking diagonals at a trot.
Louie did great, as always, and definately showed us that he is quite comfortable as a driving horse- pulling me along as if he's done it all his life. So we got the all clear tonight to go ahead and hook and drive by ourselves. We will have one final lesson next week, to re-visit the front of the barn where we had our accident, and for troubleshooting any issues we come across between now and then. Our major struggles that I believe we may run into are cutting corners/not wanting to stay on path and keep a nice bend around corners, and anticipating- Louie is kindof a smarty pants and learns routines quickly, so we need to keep him on his toes all the time to prevent this.
We also got some new equipment this week- a new whip with a drop lash, and a singletree for my cart. Unfortunately the singletree did not come with all of the hardware necessary, so Steve took the yolk and caster and is going to get us fitted with some hardware to attach the singletree next week at our last lesson. This will be nice as it will help to decrease the rubbing on Louie's shoulders around our turns as the singletree turns with the horse, allowing more movement of the harness between the shafts.
Overall, I couldn't be more pleased with my little driving horse. :) The next (well, actually current) struggle is finding a saddle that fits us!