Again, where is the pivot point in pitch
Disclaimer:  I am no expert and if you get a better answer from one of the other contributors here, you should listen to them, not me.

From what I can tell, it looks like you're asking whether you can define a point that includes all downward forces on the airplane, including center of gravity and tail downforce.  As I understand it, yes you can, and this point is center of gravity, which includes all the associated downward forces.

The airplane then would pitch about the center of gravity, as it usually does.