Michael,

I greatly appreciate the efforts you have gone to on this.

Maybe Karsten's solution then is the best way to go, but only if his cone arrowheads could be made to be scale independent (ie always small).

Another possible work around would be to have 2 perpendicular associated planes with each vector, like shown below, however with only one arrow displayed at any one time. The display would be triggered on/off (or off/on) based on angle of incidence to screen view.


Again thanks you so much for looking to solve this
James
https://www.instagram.com/nodeology/

PS the work you have done to date for display "flat to screen" will find utility with the "Numbering" node