Make an object follow camera's rotation, towards the center

Question

I have an object, which has the following code:

    [SerializeField]
    Transform target;
    [SerializeField]
    Vector3 defaultDistance = new Vector3(0f, 2f, -10f);
    [SerializeField]
    float distanceDamp = 2f;
    [SerializeField]
    Vector3 defaultPos;
    Transform myT;

    // Use this for initialization
    void Awake () {
        myT = transform;
        defaultPos = this.transform.position;
    }

    // Update is called once per frame
    void LateUpdate () { 
Vector3 toPos = target.position + (target.rotation * defaultDistance);
        toPos = new Vector3(toPos.x, 1f , toPos.z);
        Vector3 curPos = Vector3.Lerp(myT.position, toPos, distanceDamp * Time.deltaTime);
        myT.position = curPos;
}

What I'm trying to achieve:

I want the object(cube in this example, but then GUI in VR) to follow Main Camera's rotation, meaning I want the object to Lerp into the center of the camera's view when it rotates. When removing the line of code toPos = new Vector3(toPos.x, 1f , toPos.z); and adding the LookAt function, If I use a GUI/Cube/etc, it works perfectly, the object is always moving towards the center of the camera. BUT - I don't want the object to move towards the center when I rotate my camera Up/Down on the X-Axis. Thus, I wrote that line toPos = new Vector3(toPos.x, 1f , toPos.z); and now I have a bug, when I rotate the camera on the X-Axis (Meaning, up/down), after some degrees of X-axis rotation, the object starts moving on Z-Axis towards the camera's position, Instead I don't want it to move at all when I rotate upwards/downwards.

I have worked it around with eulerAngles, but It's not the solution I'm looking for because I need to define a range of degrees which still makes the object lift a bit up/down. I want it to move only on circular way around the camera on any rotation. (I've the circular movement code, but I wasn't able to implement it to my needs above)

Here's the eulerAngles code:

if (target.rotation.eulerAngles.x >= 350 || target.rotation.eulerAngles.x <= 10)
{
    Move the object towards the camera's view
    Vector3 toPos = target.position + (target.rotation * defaultDistance);
    Vector3 curPos = Vector3.Lerp(myT.position, toPos, distanceDamp * Time.deltaTime);
    myT.position = curPos;
}
else //Return the object to it's position and Y=1 (goes down/up accordingly to camera)
{
    Vector3 curPos = Vector3.Lerp(myT.position, new Vector3(myT.position.x, 1, myT.position.z), distanceDamp * Time.deltaTime);
    myT.position = curPos;
}

EDIT: This is what I've achieved so far, The cube doesn't center on the middle yet, but it circly rotates around the camera's rotation.

 Vector3 toPos = target.position + target.rotation * new Vector3(defaultDistance.x, 0.0f, defaultDistance.z);
        float multiplier = Mathf.Sqrt(defaultDistance.x * defaultDistance.x + (defaultDistance.z) * (defaultDistance.z));
        //multiplier /= Mathf.Sqrt(toPos.x * toPos.x + toPos.z * toPos.z); 
        toPos.x *= -multiplier;
        toPos.y = target.position.y + defaultDistance.y;
        toPos.z *= -multiplier ;
        toPos.z -= 70;

        Vector3 curPos = Vector3.Lerp(myT.position, toPos, distanceDamp * Time.deltaTime);
        myT.position = curPos;

EDIT 2: Almost perfect now with toPos.z -= 60;

Answer 1

Would this do the trick?

Vector3 targetPos = target.position;
targetPos.y = transform.position.y;
Quaternion newRotation = Quaternion.LookRotation(targetPos - transform.position);
transform.rotation = Quaternion.Lerp(transform.rotation, newRotation, 0.5f);