Try finding 12 EEEEEE for people with high arches. New Balance is the only running shoe I can wear because they actually make a 12 6E.
I went into a big box shoe store one time and they didn't have a single pair of shoes or boots in the whole store that fit. The salesman told me to get an operation on my feet so that I could wear their shoes.
Red Head had snake boots that fit, but then they changed the last a few years ago and I can't even get the new ones on now. The soles on my old pair have disintegrated, and I don't know if they can be resoled because of how they are made.
I have to wear rubber knee boots hunting because I haven't been able to find a pair of leather boots that fit in over 5 years. My only pair of rubber boots that fits is wearing out and I am going to have to cut down hip boots to make knee boots because nobody makes a rubber knee boot that fits anymore. NOBODY!