From camera RenderTexture to Screen Space Shader for each eye.

I'm trying to make a shader that overlaps a second VR camera view over the actual VR game screen.
I have the main VR camera and in another part of the scene i have a second camera (that follows every movement the main camera makes) that renders into a renderTexture (one for each eye).

Now i'm trying to overlap the second cameras rendertextures over the screen on each eye in the shader.
The problem is that i can't get he rendertexture to fit the eye. No matter what i do it either has an offset or not the whole render texture is showing (repeating pixel-lines on the edges) or zoomed in/out.

(I'm working in lightweight renderpipe line and single-pass stereo rendering

Code (CSharp):

1. Shader "Custom/DimensionShader"
2. {
3.     Properties
4.     {
5.         _EffectText  ("Effect Texture", 2D) = "white" {}
6.  
7.         _LeftEyeTexture("Left Eye Texture", 2D) = "white" {}
8.         _RightEyeTexture("Right Eye Texture", 2D) = "white" {}
9.  
10.         _Delta("Delta", Float) = 0
11.     }
12.     HLSLINCLUDE
13.  
14.         #include "PostProcessing/Shaders/StdLib.hlsl"
15.  
16.         TEXTURE2D_SAMPLER2D(_MainTex, sampler_MainTex);
17.         TEXTURE2D_SAMPLER2D(_LeftEyeTexture, sampler_LeftEyeTexture);
18.         TEXTURE2D_SAMPLER2D(_EffectText, sampler_EffectText);
19.         half4 _MainTex_ST;
20.         float _Delta;
21.  
22.         float4 Merge(VaryingsDefault i, float4 col)
23.         {
24.             int eyeIndex = 0;
25.             #if UNITY_SINGLE_PASS_STEREO
26.             eyeIndex = unity_StereoEyeIndex;
27.  
28.             float4 scaleOffset = unity_StereoScaleOffset[unity_StereoEyeIndex];
29.        
30.  
31.             float2 screenUV = (i.texcoordStereo.xy- (scaleOffset.zw )) / (scaleOffset.xy);
32.             float4 leftEyeCol = SAMPLE_TEXTURE2D(_LeftEyeTexture, sampler_LeftEyeTexture,              UnityStereoScreenSpaceUVAdjust(screenUV, _MainTex_ST));
33.  
34.             float4 texCol = SAMPLE_TEXTURE2D(_EffectText, sampler_EffectText, UnityStereoScreenSpaceUVAdjust(i.texcoord, _MainTex_ST));
35.             #endif
36.  
37.             float4 newCol = leftEyeCol;
38.             float ratio = texCol.r+_Delta;
39.             if (ratio > 1)
40.                 ratio = 1;
41.             if (ratio < 0)
42.                 ratio = 0;
43.             newCol.rgb = lerp(col.rgb, secCol.rgb, ratio);
44.  
45.             if (eyeIndex==0)
46.                 return newCol;
47.             else
48.                 return col;
49.         }
50.     ENDHLSL
51.  
52.     SubShader
53.     {
54.         Cull Off ZWrite Off ZTest Always
55.  
56.         Pass
57.         {
58.             HLSLPROGRAM
59.  
60.             #pragma vertex VertDefault
61.             #pragma fragment frag
62.             #pragma multi_compile __ STEREO_RENDER
63.             #pragma target 3.0
64.  
65.             sampler2D _LeftEyeTexture;
66.             sampler2D _RightEyeTexture;
67.          
68.             float4 frag (VaryingsDefault i) : SV_Target
69.             {
70.                float4 col;
71.              
72.  
73.                 float2 screenUV = i.texcoordStereo.xy;
74.                 #if UNITY_SINGLE_PASS_STEREO
75.                 float4 scaleOffset = unity_StereoScaleOffset[unity_StereoEyeIndex];
76.                     //screenUV = (screenUV - scaleOffset.zw) / scaleOffset.xy;
77.                 #endif
78.                 col = SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex,UnityStereoScreenSpaceUVAdjust(screenUV, _MainTex_ST));
79.                 col = Merge(i, col);
80.              
81.                 return col;
82.             }
83.             ENDHLSL
84.         }
85.     }
86. }
87.  

P.S. I'm a complete shader noob so i won't understand all shader-terms/words/syntaxes/whatever. I don't