Hi,
I think using the Custom depth buffer could be helpful in your case. There is an example of something similar to what I think you would like to achieve here:
http://www.tomlooman.com/the-many-uses-of-custom-depth-in-unreal-4/
I am terribly new to UE myself but stumbled upon this during my research, so you probably have to ask any questions over there…
Cheers,
J