Well, forget about what Hertz would do because whether they are an additional authorized driver or not, what will happen in 99.99% of cases is:

-Your insurance company will deny your claim because you were not driving the vehicle.

-The driver's insurance company will deny the claim because they are not legally responsible for the car...you are.

-You're screwed. If you still care what Hertz will do after finding out that you owe the amount of the car then Hertz, at the very least, will put you on their Do-Not-Rent list and if you show up at any Hertz counter you will get a nice, "Thanks but we don't want your business."

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If you really need someone to drive the rental car other than your spouse then you should always accept LDW & LIS with those rentals & declare them as drivers. It is expensive but if the car gets in an accident you will thank yourself over and over again. The only exception to this would be if you are renting for business and are with a company where LDW & liability are included in the rate and fellow employees are automatically considered authorized operators.