OP, I'm planning to do something similar when my daughter and I go next August. I booked the Bounce Back special during out December trip for five nights at Pop. This will come after of a week at BCV with friends in July. My daughter will be 16, and she enjoys fine dining as much as I do. CA Grille is our favorite. Our plan is to eat at a double credit TS restaurant every night and split the meal. I anticipate ordering an extra appetizer perhaps, and a glass of wine, to which I will add an extra tip. I think there will still be more than enough food to keep us both happy, especially if we used our CS and snack credits during the day!
I know that when we first order, the server will not know of my plans to add to the tip, but I hope it isn't a problem.