Can I bypass having to hit launch in the launcher with a command line argument?

Is there a command-line argument i can add to make the launcher automatically launch the game?

Yes!
Assuming you set up your CommandLine.txt file in the same directory as the launcher, you just need to type in the following:

-launch

This will launch your game with your last enabled mods. (Note, the launcher might still take time to load).
You can find more about command lines on this page.