Exit trigger with key press

Scripting
1

Hello,
I want to make a controllable turret. The player can walk up to a trigger and a guncamera is being enabled and the player itself is being disabled. When you don’t want to shoot the turret any longer, you can press a key and the player is being enabled again, and the guncamera is being disabled.
I then made a script that supports this. I can walk up to the turret and start shooting but I cannot exit the turret again. Do you have an idea?
Script:

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class GunExit : MonoBehaviour {

    public GameObject player;
    public Transform getOutPosition;    // Position where the player should be enabled when exitting.
    public GameObject cam;              // Camera for the turret.
    public GameObject propModel;        // A mesh that is being enabled when not using turret.

    public bool isPlayerIn = false;     // Check if in trigger.

    // Use this for initialization
    void Awake () {

        if (!getOutPosition)
        {
            GameObject getOutPos = new GameObject("Get Out Position");
            getOutPos.transform.SetParent(transform);
            getOutPos.transform.localPosition = new Vector3(-1.5f, 0f, 0f);
            getOutPos.transform.localRotation = Quaternion.identity;
            getOutPosition = getOutPos.transform;
        }
    }

    void Start ()
    {
        cam.SetActive(false);
        propModel.SetActive(true);
    }
   
    // Update is called once per frame
    // Walk in trigger and enables all the things that needs to be present.
    void OnTriggerEnter (Collider other) {
        if(other.tag == "Player")
        {
            isPlayerIn = true;
            cam.SetActive(true);
            propModel.SetActive(false);
            player.SetActive(false);
            if (Input.GetKeyDown(KeyCode.F))        //Here the player can press F and he will be controllable again, and the turret is being disabled.      
            {
                player.transform.SetParent(null);
                player.transform.position = getOutPosition.position;
                player.transform.rotation = getOutPosition.rotation;
                player.transform.rotation = Quaternion.Euler(0f, player.transform.eulerAngles.y, 0f);
                cam.SetActive(false);
                player.SetActive(true);
                isPlayerIn = false;
                propModel.SetActive(false);
            }
        }


    }
}
2

OnTriggerEnter is only called once you enter the trigger, in that single frame. So you’ll need to keep track of the Input in Update():

void Update()
{
    if(isPlayerIn && Input.GetKeyDown(KeyCode.F))
    //Enable player control and disable turret here
}