The Making of Star Trek
But I think that the dish on the front of the engineering hull has been generally accepted to be a "deflector" dish, not a "sensor" dish.
is very specific on that: It's the "main sensor-deflector". And if you don't like the double function then it's the main sensor. The Jefferies schematic with the descriptions may not have identified the three lights at the bow, but the parabolic dish is identified as "Main Sensor".
I can't see why windows for the three bow lights would seem "too unlike TOS and more like TNG". On the contrary, the whole idea that sensors or deflectors light up is a post-TOS concept introduced in TMP and TNG, IMHO.