good luck, it is actually much harder than it looks.
the cutoff frequency doesn't seem change that much, but the roll of (dB per octave) does.
turned all the way down, you even get a resonance.
so far, I never heard a convincing tone knob simulation from an EQ.
this would also only work in a reamping scenario, since the tonal change is of course pre gain
I agree. For all the reasons I mentioned above (and likely a few more that I missed), it isn't just a simple LPF.