I’ve been trying to figure this out myself. I know a person who is consistently bidding in the US without being removed. I see others come and go for short periods but this particular person is always bidding. Kudos to him for figuring it out.
Truthfully, if you were in the know of how to bypass Google’s restrictions, would you share it? Why, so your competitors can drive up your ppc costs. I think this is something you’re going to have to test and figure out on your own.