Creating a Water Surface with a Texture-shaped Hole For Android

I'm trying to make a hole into an animated water surface. The hole's shape needs to be controllable with a custom texture. I have the water surface as a simple, extremely large plane, and the hole needs to be cut under the player's boat (so the player can see through the water's surface), so the hole must be mobile.

Currently, I've done the hole with a projector based on some replies in this post: http://forum.unity3d.com/threads/projecting-a-hole.35808/

This works with the WebPlayer, but doesn't work with Android, which I desperately need as well. Apparently, the cause is probably this: http://forum.unity3d.com/threads/colorbuffer-alpha-channel-doesnt-work-on-android-devices.253233/

The projector based hole did work with Android with Unity version 4.1.5, but I need features that are only available in later Unities (and the hole shader doesn't work in versions 4.3.X - 4.5.X).

Might there be other solutions to get the hole to work?

Here are the shaders I'm currently using.

Shader on the water surface:

 Shader "FX/Water Cutoff" {
 
 Properties {
     _horizonColor ("Horizon color", COLOR)  = ( .172 , .463 , .435 , 0)
     _WaveScale ("Wave scale", Range (0.01,0.15)) = .07
     _ColorControl ("Reflective color (RGB) fresnel (A) ", 2D) = "" { }
     _ColorControlCube ("Reflective color cube (RGB) fresnel (A) ", Cube) = "" { TexGen CubeReflect }
     _BumpMap ("Waves Normalmap ", 2D) = "" { }
     WaveSpeed ("Wave speed (map1 x,y; map2 x,y)", Vector) = (19,9,-16,-7)
     _MainTex ("Fallback texture", 2D) = "" { }
 }
 
 CGINCLUDE
 // -----------------------------------------------------------
 // This section is included in all program sections below
 
 #include "UnityCG.cginc"
 
 uniform float4 _horizonColor;
 
 uniform float4 WaveSpeed;
 uniform float _WaveScale;
 uniform float4 _WaveOffset;
 
 struct appdata {
     float4 vertex : POSITION;
     float3 normal : NORMAL;
 };
 
 struct v2f {
     float4 pos : SV_POSITION;
     float2 bumpuv[2] : TEXCOORD0;
     float3 viewDir : TEXCOORD2;
 };
 
 v2f vert(appdata v)
 {
     v2f o;
     float4 s;
 
     o.pos = mul (UNITY_MATRIX_MVP, v.vertex);
 
     // scroll bump waves
     float4 temp;
     temp.xyzw = v.vertex.xzxz * _WaveScale / unity_Scale.w + _WaveOffset;
     o.bumpuv[0] = temp.xy * float2(.4, .45);
     o.bumpuv[1] = temp.wz;
 
     // object space view direction
     o.viewDir.xzy = normalize( ObjSpaceViewDir(v.vertex) );
 
     return o;
 }
 
 ENDCG
     
 // -----------------------------------------------------------
 // Fragment program
 
 Subshader {
     Tags { "Queue" = "Transparent+300" "RenderType"="Opaque" }
 
     Pass {
     Blend OneMinusDstAlpha DstAlpha
 
 CGPROGRAM
 #pragma vertex vert
 #pragma fragment frag
 #pragma fragmentoption ARB_precision_hint_fastest 
 
 sampler2D _BumpMap;
 sampler2D _ColorControl;
 
 half4 frag( v2f i ) : COLOR
 {
     half3 bump1 = UnpackNormal(tex2D( _BumpMap, i.bumpuv[0] )).rgb;
     half3 bump2 = UnpackNormal(tex2D( _BumpMap, i.bumpuv[1] )).rgb;
     half3 bump = (bump1 + bump2) * 0.5;
     
     half fresnel = dot( i.viewDir, bump );
     half4 water = tex2D( _ColorControl, float2(fresnel,fresnel) );
     
     half4 col;
     col.rgb = lerp( water.rgb, _horizonColor.rgb, water.a );
     col.a = _horizonColor.a;
     return col;
 }
 ENDCG
     }
 }
 
 }
 
 }
 

And the shader for the projector:

 Shader "Transparency Projector" {    
 
 Properties {_MainTex ("Cookie", 2D) = "" {TexGen ObjectLinear}}
 
 SubShader
 {
     Tags {"Queue" = "Transparent+10"}
     Pass
     {
         ColorMask A           
         SetTexture[_MainTex] {Matrix[_Projector]}
     }   
 }
 
 }