I think you should definetly do 4H shows. In 4h, the classes are mostly judged on you and how well you and your horse work together. Also, the pattern is a major part of the class. Only a fraction is judged on the horse itself and its conformation. Even though your horse does have very nice conformation ;)
Just make sure he has his basics down. Walk, trot, back, setting up, turn on honches, turn on forhand, and even a sidepass. This way youll be ready.
Well, I hope this helps and good luck!