We don't have any non-tox only areas in where I hunt, but I know there are a few areas that are non-tox specific and lead buck would not be allowed. What areas are you hunting? I remember when we used to go up to northern Iowa to duck hunt that a lot of the WPA areas were non-tox only, and here and there certain county areas have been made that way. Most of them are posted pretty well if they are.
For those areas I'd use Hevi-shot of some variety if I was hunting them with a shotgun.