I always have to check out your Kitty photos -- she's my kind of horse, and I agree that you need to get her driving.
I have no doubt that Portia loved her. If you could get her to Portia for driving training, you won't go wrong -- she is an incredible trainer and always keeps the horse's best interests at heart.
Just an aside: my wild boy (Mingus) is still quite a challenge in-hand, but show him a cart and he suddenly becomes all business. He knows his job and is so proud of it. Definitely get the best trainer for her, but don't assume she'll be too much in harness.