Is your server still open? And you were going to give me access to your router?
So your users are not smart enough to not enable passive in IE, or to uncheck it.. or use a real ftp client to access site so they can set passive or active based on site, etc..
But you going to have them use a SSH tunnel to get to your ftp server?? Yeah that makes sense

if your going to go the SSH route -- why not just setup SFTP? the openssh will provide SFTP, and kill 2 birds with 1 stone.. BTW yes ftp tunneled thru ssh or SFTP is way moe secure than FTP but it does come with a performance hit as its price.. You have the added overhead of encryption.
BTW -- normally in FTP over SSH, only the control traffic, ie port 21 is secured. The data connection would be in the clear and would still be either a passive or active connection.. So doing a ssh ftp tunnel is not going to fix your passive issue.
Unless your using clients that understand it, etc.