OK, go with the indirect path; he will just find more sponsors who will come in after the act. I understand the tactic, but you are hoping it will have an effect on him. If he keeps making money he won’t care.
I believe the best effect will be acheived by going for the target, not the target’s current financing.
Nope. The whole point is that if advertisers want to stay away from his show CBS will see he is toxic. The new ads will be targeted in the same way. When CBS sees that ads on Letterman get in trouble, they’ll be hurt.