I'm routing most of my traffic through a SSN tunnel proxy running on my router to a server in the US. But I want to QoS that traffic, so that my FTP traffic is de-prioritized. How can I do this?

I can have my FTP client use a different proxy from my browser. I could easily create multiple SSH tunnels and bind them to different ports, but the tunnels all go out as port 22 to the US server. How can I QoS based on the incoming port, not the outgoing port?

Could I potentially create another IP as an "alias", QoS that IP, and use that as the low priority tunnel?

Thanks in advance.

You can use the default configuration in conjunction with a rule in the Prerouting chain?