Adding Transparency/Fading Functionality to a Shader

I have a shader I borrowed from a blog (http://bernieroehl.com/360stereoinunity/) whose purpose is to allow textures to be viewable from the inside of the mesh. I currently need to add a means of the mesh fading away, but I cannot seem to successfully add an alpha component or another means to the shader script to accomplish this. Any suggestions would be appreciated.

 // Based on Unlit shader, but culls the front faces instead of the back
 Shader "InsideVisible" {
 Properties {
     _MainTex ("Base (RGB)", 2D) = "white" {}
 }
 SubShader {
     Tags { "RenderType"="Opaque" }
     Cull front
     LOD 100
     
     Pass {  
         CGPROGRAM
             #pragma vertex vert
             #pragma fragment frag
             
             #include "UnityCG.cginc"
 
             struct appdata_t {
                 float4 vertex : POSITION;
                 float2 texcoord : TEXCOORD0;
             };
 
             struct v2f {
                 float4 vertex : SV_POSITION;
                 half2 texcoord : TEXCOORD0;
             };
 
             sampler2D _MainTex;
             float4 _MainTex_ST;
             
             v2f vert (appdata_t v)
             {
                 v2f o;
                 o.vertex = mul(UNITY_MATRIX_MVP, v.vertex);
                 // ADDED BY BERNIE:
                 v.texcoord.x = 1 - v.texcoord.x;                
                 o.texcoord = TRANSFORM_TEX(v.texcoord, _MainTex);
                 return o;
             }
             
             fixed4 frag (v2f i) : SV_Target
             {
                 fixed4 col = tex2D(_MainTex, i.texcoord);
                 return col;
             }
         ENDCG
     }
 }
 
 }