[IngoRap]

I think it's a bad idea to go below the values I'm using, as you'll likely not be to control the temp adequately. The CPU/GPU clockspeeds are already dynamic, and we're dealing with a ULV processor - there's no room for tweaking there.

There is always room for tweaking.
Intel, just like any other manufacturer, goes the safe route and sets voltages, that are rather high to ensure that the processor is stable, without much testing - it doesn't matter, that it's a ULV processor. Even smartphone SoCs that are binned best/fastest can oftentimes handle their tasks with much lower voltages.

Despite the clockspeeds being dynamic, while video playback the CPU sits at 1,4 GHz with less than 10 % load. I feel like it would be worth trying, to either lock it at a P-State with lower frequency or maybe a less "aggressive" governor?

Your settings for fanspeed might be good, but people with enough knowledge might want to make their own experiences, with their specific setup.