Route traffic from some lan ip through tor whonix gateway inside main lan?

RouterOS Beginner Basics
1

I have pc with whonix which is inside main lan, for example lets say whonix gateway tor ip is 192.168.7.11. (everything is connected to one mikrotik router connected to isp)
Now i would like to make some policy based routing on this mikrotik so traffic from 192.168.8.1 will be transferred normally through isp,
but traffic from 192.168.9.1 will go only through tor gateway.

How to do that?
my guess is mangle packets from 192.168.9.1, mar prerouting, add gateway from ip route?
do i have to also ad some srcnat masquerade?

2

Your guess seems correct. Masquerade shouldn’t be necessary, if tor gateway has route to 192.168.9.1. If it’s not via the main router (which will be routing 192.168.9.1 to tor gateway), it will create asymmetric routing and firewall on router may complain about invalid packets. Masquerade would be one way to solve it. Or you can make sure that packets from 192.168.9.1 to tor gateway are always allowed.