How to remove Spline mesh in distant view

Hi everyone, I need your help again.

I’m trying to speed up the fps in my project, so I wanna remove the railways and fences in the distant view which is made by Spline Tool.

I tried to use the LODs but it can’t import an empty file as the lowest LOD.

So I wonder that is there any other way to make it possible?

And is there any way to check the total number of polygon when I play it in new window?

Forgive my poor English but I hope it makes sense.

Waiting for your reply and thank you all the way.