Forum is back finally!
So I've been experimenting and confusing myself with this a lot .. and I have a working solution now (almost)
Just using the random inductor I posted a pic of earlier, a 1000uF cap, and a FR104 diode out of the same PSU, running at 32Khz, everything is dead silent, which is great .. best of all it works, and nothing is heating up excessively.
Measuring directly across the legs of the inductor, I seem to get about 70Vpp, however measuring across the FET between drain and source, I get about 20Vpp, which seems acceptable. The FET isn't heating up either, so it must be OK with it.
However, now I seem to have an EMI issue with the microcontroller
This may have been an issue even with the RC filter - but I assume it's because I upped the PWM frequency to 32Khz, so it's just spewing out RF everywhere. The inductor probably isn't helping either.
What would be some ways I could try cut down on this EMI a bit? Ferrite bead on the wires running between the FET and filter perhaps?
I'm glad the LC filter works, and works well