Hey
@ReAktwo , I've more or less got the same setup as you and had a similar issue recently.
I would suggested watching this video:
It's a bit long and at times unnecessarily complex but it ultimately helped me get a better understanding of ways to work around this issue.
In short, set your flashes on manual, let your shutter speed control the power output of your flash. Keep an eye on the distance specified on the back of your flash and set it at a corresponding distance to your subject.
Since I started using the distance meter thing on the back of the flash, flash photography has become much easier to understand.