I think it would've been fine to adjust your EQ controls in the middle of the set. As long as you're not making extreme adjustments it you should be able to tweak things to your liking. You have put such a big emphasis on having your sound - using all your effects and amplification - but then are not willing to make a small EQ adjustment to suit your taste.
Are you saying you run HPF at 80hz? That alone could take you out of the subs and definitely can contribute to a harsh sound. It's possible that all the mids/treble in your tone would've been balanced out nicely if there was more low end in your signal. So the soundguy was maybe not completely wrong.
For the treble tweaking on the fly, as I Said, I didn't know if the trebles in FOH had been adjusted yet, and didnt want to reduce them fearing dulling my tone. In doubt, left them !
Yes High pass at 80 KHz, but it is my usual setting on recording and it sounds fine. Also I used the very same setting ( appart for the GK 7kHz treble knob) the previous week with another soundguy and everything was fine.
So with that I don't really trust the " There is nothing under 200 Hz "
I just think it was more " You have a LOT of 250 Hz low mid and 1Khz High mid and too much 7Khz trebles " and more important : " this is not the basic standard bass tone I was expecting "