ForceFrustum

using UnityEngine;

//PUT THIS BEHAVIOUR LATE IN YOUR SCRIPT EXECUTION ORDER

public class FrustumCullingHack : MonoBehaviour
{
    public MeshFilter meshFilter;

    void Update()
    {
        Transform camTransform = Camera.main.transform;
        float distToCenter = (Camera.main.farClipPlane - Camera.main.nearClipPlane) / 2.0f;
        Vector3 center = camTransform.position + camTransform.forward * distToCenter;
        float extremeBound = 500.0f;
        meshFilter.sharedMesh.bounds = new Bounds(center, Vector3.one * extremeBound);
    }
}