I would definitely run a BTA water bottle. Studies have indicated that it is actually an aero gain by itself, let alone the better access to hydration. I personally prefer a regular cage and WB between my arms, but if you can get something like the Torhans Aero 30 system to snug right up against the head tube, it is a very fast system.
Nice job on her position…a great example how you don’t always have to go lower with your HB in order to lower the upper body. Extending 9and raising) the reach can accomplish the same thing.