Modified creation of shadowmap, so subclasses can override texture settings before the RTID gets created.

Assets/ScriptableRenderPipeline/Core/Shadow/Shadow.cs

     public class ShadowAtlas : ShadowmapBase, IDisposable
     {
         public const uint k_MaxCascadesInShader = 4;
-        protected readonly RenderTexture              m_Shadowmap;
-        protected readonly RenderTargetIdentifier     m_ShadowmapId;
+        protected          RenderTexture              m_Shadowmap;
+        protected          RenderTargetIdentifier     m_ShadowmapId;
         protected          VectorArray<CachedEntry>   m_EntryCache = new VectorArray<CachedEntry>( 0, true );
         protected          uint                       m_ActiveEntriesCount;
         protected          FrameId                    m_FrameId;
 
         public ShadowAtlas( ref AtlasInit init ) : base( ref init.baseInit )
         {
-            m_Shadowmap             = new RenderTexture( (int) m_Width, (int) m_Height, (int) m_ShadowmapBits, m_ShadowmapFormat, RenderTextureReadWrite.Linear );
-            m_Shadowmap.hideFlags   = HideFlags.DontSaveInEditor | HideFlags.DontSaveInBuild;
-            m_Shadowmap.dimension   = TextureDimension.Tex2DArray;
-            m_Shadowmap.volumeDepth = (int) m_Slices;
-            m_ShadowmapId           = new RenderTargetIdentifier( m_Shadowmap );
-
             if( !IsNativeDepth() )
             {
                 m_TempDepthId = Shader.PropertyToID( "Temporary Shadowmap Depth" );
         }
 
+        public override void CreateShadowmap()
+        {
+            m_Shadowmap = new RenderTexture( (int) m_Width, (int) m_Height, (int) m_ShadowmapBits, m_ShadowmapFormat, RenderTextureReadWrite.Linear );
+            CreateShadowmap( m_Shadowmap );
+        }
+
+        virtual protected void CreateShadowmap( RenderTexture shadowmap )
+        {
+            m_Shadowmap.hideFlags   = HideFlags.DontSaveInEditor | HideFlags.DontSaveInBuild;
+            m_Shadowmap.dimension   = TextureDimension.Tex2DArray;
+            m_Shadowmap.volumeDepth = (int) m_Slices;
+
+            m_ShadowmapId = new RenderTargetIdentifier( m_Shadowmap );
+        }
+
         override protected void Register( GPUShadowType type, ShadowRegistry registry )
         {
             ShadowPrecision precision = m_ShadowmapBits == 32 ? ShadowPrecision.High : ShadowPrecision.Low;
             m_Flags |= (base.m_ShadowmapFormat == RenderTextureFormat.RGFloat  || base.m_ShadowmapFormat == RenderTextureFormat.RGHalf) ? Flags.channels_2 : 0;
             m_Flags |= SystemInfo.usesReversedZBuffer ? Flags.reversed_z : 0;
 
-            m_Shadowmap.enableRandomWrite = true;
             m_SampleCount  = 1; // TODO: Unity can't bind msaa rts as textures, yet, so this has to remain 1 for now
             m_MomentBlurCS = Resources.Load<ComputeShader>( "ShadowBlurMoments" );
 
                 for( int j = 0; j < m_BlurWeights[i].Length; ++j )
                     m_BlurWeights[i][j] *= weightSum;
             }
+        }
+
+        override protected void CreateShadowmap( RenderTexture shadowmap )
+        {
+            shadowmap.enableRandomWrite = true;
+            base.CreateShadowmap( shadowmap );
         }
 
         private void FillBlurWeights( int idx )
             m_Shadowmaps = shadowmaps;
             foreach( var sm in shadowmaps )
             {
+                sm.CreateShadowmap();
                 sm.Register( this );
                 sm.ReserveSlots( m_ShadowCtxt );
                 ShadowmapBase.ShadowSupport smsupport = sm.QueryShadowSupport();

Assets/ScriptableRenderPipeline/Core/Shadow/ShadowBase.cs

         abstract public void Update( FrameId frameId, ScriptableRenderContext renderContext, CullResults cullResults, VisibleLight[] lights );
         abstract public void ReserveSlots( ShadowContextStorage sc );
         abstract public void Fill( ShadowContextStorage cs );
+        abstract public void CreateShadowmap();
         abstract protected void Register( GPUShadowType type, ShadowRegistry registry );
         abstract public void DisplayShadowMap(ScriptableRenderContext renderContext, Vector4 scaleBias, uint slice, float screenX, float screenY, float screenSizeX, float screenSizeY);
     }