How can i render Enviroment shadows to my weapon camera

Hey there I need some help I have 2 cameras MainCamera that capture all the object in the scene but not the View models of the guns that are render in the second camera called Weapon camera and i want to get the Enviroment shadow of the objects in the scene render of the gun models without seeing the env models in the weapon camera.
How can i acive that? pls help me

  1. Add a light.
  2. Go to the side of the terrain, and look at how it goes up and down, and make a countour image/sprite, but 3d-ish.
  3. Attach that image/mesh to the camera, but make it so that it is out of the cameral view, but still moves with the camera.

I hope I was of help.