»»"the guitar is an equal tempered instrument"
»»Not if you play it properly.

Dave MacKenzie,
I have always had an ear for the pure intervals and find fretted instruments, and all fixed-intonation instruments, to be very frustrating in this regard.
Best I can figure, to play guitar in a meantone or any untempered scale would require tweaking an open tuning to the intervals used in the desired scale, then changing chords using only pure barres, never any other fingering. But this isn't what most people would call playing "properly" with the exception of slide guitar. But I'm talking about just plain old regular chording, maybe some fingerpicking or plucking, definitely some strumming.
If there's another way to play guitar in meantone or just intonation, it would make my day to know what it is!

Thanks in advance!