James has a nice video here which also includes an example of how to set up a material parameter collection as light vector: Unreal Engine - [Live Stream] Demystifying The Dot - YouTube
In the video he sets the directional light’s position for the vector parameter via the planet’s BP, but in your case you can set that value in level blueprint and all the materials that use that parameter will use that vector value as the light vector so you dont need to set it for every actor separately.
Hope it helps!