[W]hat about banning trade with China?

This really does far less for American workers than many imagine. Banning trade with China does not affect a decision to off-shore an operation to Vietnam, or Bangladesh, or Mexico. Whether an operation moves from the U.S. to China or from the U.S. to Bangladesh does not materially alter the outcome for the displaced U.S. workers.

In view of your “expect[ation that[ the second term [will] make the first look like a light warmup,” I suppose that the follow-up will be “well, what about banning all imports?” Two points about that:

(1) It cannot be done. The war on drugs has shown what follows when you try to stop a transaction between a willing buyer and a willing seller. You can gum up the works—make the transactions slower, or costlier—but you cannot really stop the transactions en masse. And that is an example drawn from a product (intoxicating narcotics) on which there is a widespread social opprobrium. Imagine how ineffective will be the interruption to mutually agreeable commerce when the products being stopped are garments, or winter strawberries, or car tires (etc)—things that no one regards as wrongful or injurious.

(2) As noted in my 1.1.2, this will not actually benefit U.S. workers. That sort of interruption to global supply chains will drag U.S. production down to near zero in a variety of industries.