customize spotlight near illumination plane?

Unity has been great so far. I only just ran into my first roadblock, and thought I would reach out. Please let me know if there's a better place for my question.

I am looking for a way to set the near illumination plane on a spotlight. Use the attached image as reference. I have set the shadow near-clip plane between the two cubes. However, I would also like the left most cube to remain unaffected by this light. Layers, unfortunately, are not practical in my situation as the light will move. I would like to not see the illumination on objects x-radius from the spotlight.. My questions are:

• Does this functionality exist in unity 2018.1.3f1?
• Can I edit the unity spotlight to create this effect?
  
• Can I write my own spotlight to create this effect?
• Is this better done in a surface shader?
  
• Can this be added as a feature if the above are not possible?

Apologies for any ignorance on my part, and thanks very much for your time.