I have different sized feet (full size) and I use footbeds plus stuff the toes. I did ask if Edea would do a pair of different sized boots and a European tech I chatted to thought it would be possible however when I called the NA distributor it was a flat no and they wouldn't even try contacting Edea to ask.
Depending on the level customs may be cheaper than buying two pairs, but it may also be possible to get the 8.5 stretched to fit your larger foot. From a cost position it's probably worth trying, especially as your fitter sounds really helpful and willing to work with you.