Whit,

Going by a horizontal tail is wrong, simply because what the designer cares about is the attitude of the model or real airplane for cruise speeds.

He wants the minimum drag for the more common speeds (imagine so many airliners burning extra fuel flying most of the time nose up or down).

Whatever attitude seems more natural to you should be the position for proper and accurate balance.

The incidence of the tail has nothing to do with the above considerations or the balance of the model.

The same designer selects that incidence solely based on the tail down force that he wants, without which the model would nose down (equivalent to elevator-up input) or wouldn't be stable in pitch (if no need for that force due to too aft CG (tail heavy model): model too sensitive to any elevator input).

How to obtain that negative lift from the tail?
We know that zero AOA = no lift, then some AOA is needed.
That AOA comes from the angle between the tail and the down-wash coming from the wing.

So, very frequently, the incidence of the tail respect to the datum line of the fuselage is zero, because the downwash is around 2 or 3 degrees pointing down and that creates enough tail down force, but it doesn't have to be horizontal for cases where the downwash angle is more or less than that.