Please file a safety complaint with NHTSA. There are already a number of complaints about rusted out frames on the 4th gen 4Runner. If NHTSA receives enough complaints, Toyota may start a frame replacement campaign like they did with the Tundra and Tacoma, or NHTSA may force/order Toyota to do the frame replacements. I believe that Tundra/Tacoma owners who repaired/replaced their frames before Toyota's service campaign were reimbursed, but I'm not sure.
https://www-odi.nhtsa.dot.gov/ivoq/
http://www-odi.nhtsa.dot.gov/owners...ia.make=TOYOTA&searchCriteria.prod_ids=216239
Done. Maybe it will help future owners.