setuid directories - or other option?

[Modulok]

List,

I have a media project directory shared with windows users via samba. Every
authenticated samba user that accesses the directory is forced to the same
FreeBSD user, 'foo', regardless. The group also has write-access:

    drwxrwxr-x  47 foo        foo         2.5K Feb  4 05:42 foo/

Local shell users, however, are a problem. Ideally, I want a simliar behavior
for them too i.e. Any files they create in the directory are also owned by the
user 'foo'. How do I do that? (See below about setuid.)

I wouldn't even care who owns the files, so long as file permission bits in
this directory defaulted to 664 so every member of the group 'foo' could edit
them. Can I do this without changing every user's default umask? (I want to
avoid that.) Is there some kind of 'umask for this directory is blah' feature?

I looked at setuid bit on directories. Sounds perfect! BUT I'll be moving to
ZFS soon and from what I gather, it won't work there. I guess I could have a
cron job run every minute and change offending permission bits, but that feels
hacky.

Any other ideas?
-Modulok-