DaVinci and the Tower of Books

Weird title, I know but there is an explanation.

Today brought rain. When we got to the barn it was only lightly raining so we told the college girl to come over. To start with we had her groom DaVinci and let him get to know her. We explained that DaVinci is a more sensitive, hotter horse than Dottie and can be tougher to ride. She came back with that she rides hot warmbloods at school. In my experience a hot Arab vs a hot warmblood is two different situations. I think she underestimates DaVinci because he is only 14.1h.
The rain slacked enough that I told her to ride, though she was still not convinced he could handle her size. Mom tacked him up so he was more comfortable. CG mounted and what do you know she did not look bad on him...surprise.
DaVinci gave her his wonderful "8" walk over to the arena, testing her a little by "spooking" at the little red wagon. CG has the tendency to lean forward when tense, not good on a horse like DaVinci. Mom talked her through and they walked on. Walking was good. DaVinci stretched down and chewed. Then she asked for the trot, tensed and he just went fast. His head went up, her shoulders came forward and her hand went down. One big ball of building tension. Oh boy.
Mom to the rescue. She told her to lift then roll she shoulders back and down bringing her weight down into the saddle and bringing her vertical raising her hands. I told her to breathe. Crisis averted. DaVinci started to settle and find his working trot. Sometimes she was able to get him to round, but most of the time he looked like a tourist on a European tour.
One thing we noticed is her left shoulder drops lower than her right. Just like horses if we have discrepancies it can show in our riding. While riding Dottie she mentioned the saddle slipped to the right. We did not have the same problem, but with that shoulder she could be compensating by stepping heavy on the right stirrup causing the shift. With the DaVinci I noticed tracking to the left he was almost always bent to the outside. Could be she leads with the lower shoulder too.
Another thing we noticed is that she is like me, tall in the torso. When riding smaller horses or ponies that height can easily shift a horses balance. We saw that happening to DaVinci. Mom tried to explain what was happening to CG in non horse terms.
If you are carrying a tower of books and they begin to tip forward what is the normal reaction?
The carrier tends to quicken their pace to get under the tipping tower.
A horse can react the same way to a forward shift in balance of a rider. DaVinci will teach CG about keeping her shoulders back and finding her center. Being centered helps a rider be much more solid in the saddle. Okay moving on.
Anyway her trot work improved enough we told her to ask for canter. I told her to ask for left lead since he is not as strong that way. He is trained to pick it up with the inside leg with outside rein half halt, so that was different for her. He surprised her with the transition, a very nice one, and she kind of leaned forward and grabbed the reins. Another snowball moment building, but again Mom talked her through. The downward had a bit to much hand action so DaVinci protested a little. Overall it was not as bad as it could have been.
Hopefully she will be smart and go slow with him for her sake. I trust my horses opinions and neither has had a negative reaction to CG.
Do you think she will take DaVinci a little more seriously now :)