Still having Serialization issues in 4.5.1f3

I think I understand, so I could create a struct from scratch and call it Vector3Serializable and serialize that and have it work just like a vector 3, but I cannot straight up serialize a pre-existing Vector3?

If that's basically it, i'll mark this as correct. Just want to make sure I understand. I'm only a self-taught programmer.

You are correct. I've actually got a serializable v3 if you want to just have one:

 using UnityEngine;
 using System;
 using System.Collections;
 using System.Runtime.Serialization;
 #if UNITY_EDITOR
 using UnityEditor;
 #endif
 [System.Serializable]
 public class SeriV3: ISerializable {
     public static implicit operator Vector3(SeriV3 v) {return v.v3;}
     public static explicit operator SeriV3(Vector3 v) {return new SeriV3( v );}
     public SeriV3(Vector3 v) { v3 = v; }
     public static Vector3 operator*(SeriV3 v,float f) {return v.v3*f;}
 
     public Vector3 v3;
 
     public float x { get { return v3.x; } set { v3 = v3.WithX( value ); } }
     public float y { get { return v3.y; } set { v3 = v3.WithY( value ); } }
     public float z { get { return v3.z; } set { v3 = v3.WithZ( value ); } }
 
     public void GetObjectData(SerializationInfo info, StreamingContext context) {
         // Use the AddValue method to specify serialized values.
         info.AddValue("x", v3.x, typeof(float));
         info.AddValue("y", v3.y, typeof(float));
         info.AddValue("z", v3.z, typeof(float));
     }
 
     // The special constructor is used to deserialize values. 
     public SeriV3(SerializationInfo info, StreamingContext context)
     {
         // Reset the property value using the GetValue method.
         v3 = new Vector3(
             (float)info.GetValue( "x", typeof(float) ),
             (float)info.GetValue( "y", typeof(float) ),
             (float)info.GetValue( "z", typeof(float) )
         );
     }
 
     public override string ToString ()
     {
         return string.Format ("[x={0}, y={1}, z={2}]", x, y, z);
     }
 }
 
 // my real version of this class has a thousand things in it, these are just the necessary ones for seriv3
 public static class Utex {
     public static Vector3 WithX(this Vector3 v, float x) {
         return new Vector3(x,v.y,v.z);
     }
     public static Vector3 WithY(this Vector3 v, float y) {
         return new Vector3(v.x,y,v.z);
     }
     public static Vector3 WithZ(this Vector3 v, float z) {
         return new Vector3(v.x,v.y,z);
     }
     
 }