Thanks for the advice, but I got the sizes correctly. The problem was the training of DCGAN not converging.

Sorry, I misunderstood. Somehow, I was thinking the problem was related to changing it that it can “technically” handle the change in width.

Sorry for the late reply, nope its just a wild idea. For now, I am generating  [1, 48, 64] . I would try to tweak up to  [1, 48, 84]

I would also maybe try to keep the height & widths in the hidden layers proportional to the inputs (if you are not doing it already). E.g., something like 14x24x64, or 4x8x128, etc… You could do this by changing the stride for the width.
Also, do I understand correctly that you train on 48 x 84 images but provide 48 x 64 to the discriminator?