> The customization is done here in cus-start.el
 >
 >               (resize-mini-frames
 >                frames (choice
 >                        (const :tag "Never" nil)
 >                        (const :tag "Fit frame to buffer" t)
 >                        (function :tag "User-defined function"))
 >                 "27.1")


Thanks, now I know how that is done, I should have grepped for it.

I have attached an updated patch where I implemented your suggestions.
For now I updated the tag to 27.2. Let me know if anything else could be 
improved and thanks for giving me the opportunity to contribute a little 
to my favorite software :)