If you're playing Dreamer, I think your best strategy against Freikorps is summoning chaff to tied them down. You can't get hit with a rocket launcher if you're engaging the model that needs to shoot it. You probably need to play super cagey turn one. Then once you have 2 models summoned, try to unbury them to engage as much as possible along with some hired models. If your opponent spreads out to prevent having multiple models engaged, you need to gang attack specific models to bring them down.
Go after their healing sources too.
Also you should have a large card advantage. If you can force discards, Freikorps *hates* that. They have so many friendly discard effects and TNs to hit, if you can disrupt that, they're top decking with basically average stats and less resources like focus.