People will insist on building wooden framed, oversized coops with human convenience in mind rather than trying to provide an easy to clean, parasite unfriendly design that can be cleaned with a blow torch. Nope, I haven't lost my marbles. If one is going to build a wooden coop in an region that is prone to mite infestation then this above all should be the primary consideration when designing the coop. The chickens don't care what the coop is and don't care much how big it is in temperate climates. They would much rather have the keeper spend the money on the run if kept confined.
Have you considered a recycled plastic coop. I use one these days having built numerous coops in the past and wouldn't consider anything else now. That’s what I’m using right now but it’s about to be way too small (and it’s the largest size i can get) plus the ventilation is crap. Not saying they’re all like that but the only ones available to me are.