I am making a china hutch in a Mission style. The top part is separate from the buffet and is near completion, but I have not yet glued it up. It is approx. 53" wide by 46" high. The sides are 4/4 divided light windows, the top and bottom are frame and panel solid 3/4" oak, and the back is 3/4" frame/divided light for mirrors.
I am not worried about the back as the frame squares it up perfectly. The front is only a narrow outside frame with two 7/8" by 1" divider/stiles which will house 3 divided light doors. I am working with the flattest surface I have, but I have noticed that even a little pressure to the top corners will push the frame out of square.
Is there an accepted method for dealing with this flexing? I have seen cabinets with a solid immovable door in the middle, but I don't really like that idea. Is it acceptable to have to shim the bottom to get everything at 90 degrees once you bring it inside to a less than flat floor? Any suggestions would be appreciated. Hopefully, it will become ridged enough once I glue it up.
I have attached a photo for reference (Yes my shop is a mess.)