I'd use the custom white balance setting. Grab a white balance gray card, or just a white piece of printer paper, have the someone hold it once the lighting is more or less setup, and use that to set the white balance. Simple, easy. Plus the editor can use that image to set the white balance separately or tweak it in post if they prefer. Once you have the WB set to a static value, it's simple for the editor to get white balance to the setting desired in the first image, and then paste those settings to everything else quickly and easily.
90mm TS for studio work? Interesting, I've never show with a TS, but that seems like an interesting choice.
I don't know your specific needs, but with the 24-70, I'd rent one of the 70-200L or the 135L lenses to complement if you are doing more portraiture type shots.