You may coinjoin your coins as much as you want. If you want to use them in "the land of the free" you'll have to give away your freedom and privacy by declaring them to Big Brother. Otherwise your output might just be frozen by the "law abiding merchant" that receives it.
Mixers are not enough to fight back. But I fail to see alternatives.
I know you and many other bitcoin developers have brilliant minds... I hope you manage to come up with a solution.
The alternative is to give up on "law abiding businesses" and create infrastructure that assists individuals in operating
censorship-resistant business models.