actually the partcular model 6120 Players Edition Nashville that I have is a 2.5" body, not the full 2.75" of the more historically accurate 6120s. It is a modern compromise to sacrifice some of the acoustics for more comfort.that makes a lot of sense, now that you mention it ...
for the 5410 (1/4" shallower than your 6120..
I am not an acoustics expert, but the body chamber and strings definitely interact. Feedback comes from external acoustic excitation of the body that gets transferred into the strings, for example. The total dimensions of the body are like a band-pass filter for the acoustics that can propagate in there. Those dimensions are related to the wavelengths of sound, in certain multiples and fractions of the wave, analogous to organ pipes. You need the really long larger diameter pipes for the low end bass notes, right? Deeper guitar bodies will retain more of the rich bottom end. Just look at the size of an acoustic bass compared to a violin.
How much of the body acoustics gets picked up by the magnetic pickups? That is a good question, and a large part of that is in how the body interacts with the strings themselves.