So you're suggesting that shaping to reduce RCS is something that you yourself are unable to discern???
Not to give any measurement of RCS.
In the simplest approach, because visual and radar waves don't exactly act in the same way.
There were very good american studies in 1960s, iirc, by Douglas.
Idea was exactly to make a "stealthy looking" plane, as it was perceived.(basically ancestor of a forum stealth design, by people with much, much deeper understanding of both physics and engineering, though)
The moodel was looking stealthy, and had all necessary measures. Furthermore, it looked cool and skifi-ysh, like a plane from 1990s.
It was just as visible for radar, though, and was an aerodynamic disaster.
Afterwards, all serious designs aren't eyeball RCS-designed.
Especially since people involved in design process are far, far, far ahead in relevant subjects than internet experts.
You can guess
relative attention for planes of the same generation.
You can say what some elements are going to be relatively more visible, and thus roughly estimate where spikes and lows will be.
Anything more serious ia beyond realm of eyeballung, and requires at least a computer model. Which will be an extremely rough estimation, but already an estimation.