Maybe I'll write a full post about my idea for a compromise policy between free trade and protectionism, but your mention of "mirror clauses" made me think of it.

Basically, it would be bilateral tariff rates that exactly match the trade partners' tariff rates: i.e. we won't tax your stuff at all, if you don't tax our stuff. I think the game theoretic equilibrium of that system is free trade, or very close to it.