This is exactly what I would do.

While there are prepaid options that don't cost much to keep "alive", those rarely have any service outside the US, nor is the data particularly well-priced unless you're a very light user. For one or two trips a year, it's almost certainly cheaper just to buy a new prepaid SIM shortly after arriving in the US and set up the GV forwarding for calls.

It would probably be necessary to create a new "American" Google account in order to have access to GV. At worst, this can be done on the next trip to the US so that you've got an American phone number available.

It might be possible to sign up for Fi and just pause the service when you're out of the US, but you need an American credit card to sign up. Plus, when Fi is paused, the line is dead--no calls or SMS.