Moving game objects from the second camera

I have a problem with a split screen game. The player one screen has a player running through a 2d platform environment being controlled by the keyboard being seen through the main camera, this is working fine. The player 2 screen is supposed to let a cooperative partner move & rotate platforms with the mouse but i can only get it to work on the p1Camera/main camera.

How can I get it to work on the p2Camera?

This is the code I have for platform rotation working with the main camera.

 using UnityEngine;
 using System.Collections;
 
 public class platformRotate : MonoBehaviour {
 
     private Camera myCam;
     private Vector3 screenPos;
     private float angleOffset;
     
     void Start () {
         myCam=Camera.main;
     }
     
     void Update () {
         //This fires only on the frame the button is clicked
         if(Input.GetMouseButtonDown(0)) {
             screenPos = myCam.WorldToScreenPoint (transform.position);
             Vector3 v3 = Input.mousePosition - screenPos;
             angleOffset = (Mathf.Atan2(transform.right.y, transform.right.x) - Mathf.Atan2(v3.y, v3.x)) * Mathf.Rad2Deg;
         }
         //This fires while the button is pressed down
         if(Input.GetMouseButton(0)) {
             Vector3 v3 = Input.mousePosition - screenPos;
             float angle = Mathf.Atan2(v3.y, v3.x) * Mathf.Rad2Deg;
             transform.eulerAngles = new Vector3(0,0,angle+angleOffset);
         }
     }
 }

For reference my Main camera is called "Main Camera", tagged as "MainCamera" and on a layer ignoring raycasts. And my second camera is called "p2Camera", tagged as "p2Camera" and on the default layer.