Replace the whole car. 92 corollas on the coast of California don’t have any rust to speak of, the Southern half of Ca. has even less. There is So. Dakota too but less Toyotas. Az. Nv. East of the Cascade mountains in Wa. has little rust. Take a trip out to Wenatche if my spelling is close. Chelan Wa is OK too. Don’t forget Spokane.