I went with boots that have heat moldable shells and liners. Nothing crazy expensive and REI did the heat molding which took less than 1 hour and cost less than $60 to do. They fit like a dream and I have finicky feet.
Then did the same for my wife who always complained about boot fit. She loves her new heat molded boots now.
Did you ever consider something like that? EVO has lots of good info about boot fit, measuring etc so I had no issue researching and ordering boots on line that were right.
After doing this I can't ever imagine buying anything used or non-moldable for my feet.
I don't have touring boots but this is one example of something that may work for you
Read or share reviews of the Salomon S/Lab MTN Alpine Touring Ski Boots 2023 or shop similar Boots
www.evo.com