Definitely having couple of cops on the S2 will help alot. This will allow civs to do legal as well as illegal jobs. We Mechs are always happy to get couple of us on S2 and im 100% sure that Inkery as well as all other mechs will agree with me. Myself, im happy to be on there as mech or car dealer.
The biggest thing is that I believe people like to play with the people they are "best friends" with on the community. Like in schools, there are groups of people that like to just play together and when couple of people from that group is on S1 when the server is full and the rest of that group wanna play. Rather than joining S2 they want to join S1 to be with the group of friends. That is completely fine and I understand that, however this is main cause of S2 not being populated in my opinion as other players see that there is no one on there and don't want to join an empty server.
As a community we all should be friends and want to interact with everyone and not only specific people. Due to that, I don't have as much of an idea for it as just a - Please if a group of friend could just join S2 every now and then we could have 2 servers full not just one. A group of 3-6 friends with some cops and mechs will be half of a server. Also if you see that server 1 is full with a large queue, just join S2 and start populating it and hopefully more players will join you there. I truly believe this will affect the S2 in more population.
And as always, have FUN!