I have 5 boots, 3 that I actively use. Put all the pins in or take them out, from 110 flex to 150s that won't come off, some cut up, some as they came. I skied one size larger as well... they're all different and impact skiing in different ways, but nothing on the magnitude you are indicating here... unless my feet slosh in them laterally, I don't really have a big issue - of course performance varies with fit and I definitely know what I have on me feet every time, but I can ski them all, without big issues.
I don't know - sounds like you have a lot of issues with the boots. Maybe it's really worth it considering a trip to the Harb Ski Shop, with an open mind and a pocket full of moneys. The feedback on their boot service is stellar, anywhere I look, especially for weird feet.
It will be painful to spend a bunch in one go, but you may end up spending more, a dime at a time... by now you are painfully aware of how important boots are to skiing enjoyment... and since you spend so much time in them, I would try to survive without spending more moneys, until I could make the trip.
cheers