The final step (barring any overlooked missing bits, requested refactors, and of course, rolling in dependencies already submitted as PRs) consists of:

renderPrePassMgr.cpp related:
A) shifting .addFeature( MFT_XYZ); calls from ProcessedShaderMaterial::_determineFeatures to ProcessedPrePassMaterial::_determineFeatures
B) mimicking the "// set the XXX if different" entries from RenderMeshMgr::render in RenderPrePassMgr::render
C) fleshing out ProcessedPrePassMaterial::getNumStages() so that it shares a 1:1 correlation with ProcessedShaderMaterial::getNumStages()
D) causing inline void Swizzle<T, mapLength>::ToBuffer( void *destination, const void *source, const dsize_t size )  to silently fail rather than fatally assert if a source or destination buffer is not yet ready to be filled. (support for #customTarget scripted render targets)

Reflections:
A) removing reflectRenderState.disableAdvancedLightingBins(true); entries. this would otherwise early out from prepass and provide no color data whatsoever.
B) removing the fd.features.addFeature( MFT_ForwardShading ); entry forcing all materials to be forward lit when reflected.
C) 2 things best described bluntly as working hacks:
C1) when reflected, a scattersky is rotated PI along it's z then x axis in order to draw properly.
C2) along similar lines, in terraincellmaterial, we shut off culling if it's a prepass material.

Skies: scattersky is given a pair of rotations for reflection purposes, all sky objects are given a z value for depth testing.

Engine/source/renderInstance/renderBinManager.cpp

@@ -36,7 +36,8 @@ RenderBinManager::RenderBinManager( const RenderInstType& ritype, F32 renderOrde
    mRenderInstType( ritype ),
    mRenderOrder( renderOrder ),
    mProcessAddOrder( processAddOrder ),
-   mRenderPass( NULL )
+   mRenderPass( NULL ),
+   mBasicOnly ( false )
 {
    VECTOR_SET_ASSOCIATION( mElementList );
    mElementList.reserve( 2048 );
@@ -60,6 +61,9 @@ void RenderBinManager::initPersistFields()
    addField("processAddOrder", TypeF32, Offset(mProcessAddOrder, RenderBinManager),
       "Defines the order for adding instances in relation to other bins." );
 
+   addField( "basicOnly", TypeBool, Offset(mBasicOnly, RenderBinManager),
+      "Limites the render bin to basic lighting only." );
+
    Parent::initPersistFields();
 }
 

Engine/source/renderInstance/renderBinManager.h

@@ -128,6 +128,8 @@ protected:
    /// RenderInst if available, otherwise, return NULL.
    inline BaseMatInstance* getMaterial( RenderInst *inst ) const;
 
+   // Limits bin to rendering in basic lighting only.
+   bool mBasicOnly;
 };
 
 
@@ -160,6 +162,7 @@ inline BaseMatInstance* RenderBinManager::getMaterial( RenderInst *inst ) const
 {
    if (  inst->type == RenderPassManager::RIT_Mesh || 
          inst->type == RenderPassManager::RIT_Decal ||
+         inst->type == RenderPassManager::RIT_DecalRoad ||         
          inst->type == RenderPassManager::RIT_Translucent )
       return static_cast<MeshRenderInst*>(inst)->matInst;
 

Engine/source/renderInstance/renderGlowMgr.cpp

@@ -79,6 +79,7 @@ void RenderGlowMgr::GlowMaterialHook::_overrideFeatures( ProcessedMaterial *mat,
    // the glow materials.
    fd.features.removeFeature( MFT_Fog );
    fd.features.removeFeature( MFT_HDROut );
+   fd.features.addFeature( MFT_Imposter );
 }
 
 RenderGlowMgr::RenderGlowMgr()
@@ -89,6 +90,7 @@ RenderGlowMgr::RenderGlowMgr()
                                  Point2I( 512, 512 ) )
 {
    notifyType( RenderPassManager::RIT_Decal );
+   notifyType( RenderPassManager::RIT_DecalRoad );
    notifyType( RenderPassManager::RIT_Translucent );
    notifyType( RenderPassManager::RIT_Particle );
 

Engine/source/renderInstance/renderMeshMgr.cpp

@@ -144,6 +144,14 @@ void RenderMeshMgr::render(SceneRenderState * state)
       if( !mat )
          mat = MATMGR->getWarningMatInstance();
 
+      // Check if bin is disabled in advanced lighting.
+      // Allow forward rendering pass on custom materials.
+
+      if ( ( MATMGR->getPrePassEnabled() && mBasicOnly && !mat->isCustomMaterial() ) )
+      {
+         j++;
+         continue;
+      }
 
       U32 matListEnd = j;
       lastMiscTex = sgData.miscTex;

Engine/source/renderInstance/renderObjectMgr.cpp

@@ -22,6 +22,8 @@
 #include "renderObjectMgr.h"
 #include "console/consoleTypes.h"
 #include "scene/sceneObject.h"
+#include "materials/materialManager.h"
+#include "scene/sceneRenderState.h"
 
 IMPLEMENT_CONOBJECT(RenderObjectMgr);
 
@@ -66,6 +68,10 @@ void RenderObjectMgr::render( SceneRenderState *state )
    if(!mElementList.size())
       return;
 
+   // Check if bin is disabled in advanced lighting.
+   if ( MATMGR->getPrePassEnabled() && mBasicOnly )
+      return;
+
    for( U32 i=0; i<mElementList.size(); i++ )
    {
       ObjectRenderInst *ri = static_cast<ObjectRenderInst*>(mElementList[i].inst);

Engine/source/renderInstance/renderPassManager.cpp

@@ -51,6 +51,7 @@ const RenderInstType RenderPassManager::RIT_Terrain("Terrain");
 const RenderInstType RenderPassManager::RIT_Object("Object");      
 const RenderInstType RenderPassManager::RIT_ObjectTranslucent("ObjectTranslucent");
 const RenderInstType RenderPassManager::RIT_Decal("Decal");
+const RenderInstType RenderPassManager::RIT_DecalRoad("DecalRoad");
 const RenderInstType RenderPassManager::RIT_Water("Water");
 const RenderInstType RenderPassManager::RIT_Foliage("Foliage");
 const RenderInstType RenderPassManager::RIT_VolumetricFog("ObjectVolumetricFog");

Engine/source/renderInstance/renderPassManager.h

@@ -108,6 +108,7 @@ public:
    static const RenderInstType RIT_Object;   // objects that do their own rendering
    static const RenderInstType RIT_ObjectTranslucent;// self rendering; but sorted with static const RenderInstType RIT_Translucent
    static const RenderInstType RIT_Decal;
+   static const RenderInstType RIT_DecalRoad;
    static const RenderInstType RIT_Water;
    static const RenderInstType RIT_Foliage;
    static const RenderInstType RIT_VolumetricFog;

Engine/source/renderInstance/renderTerrainMgr.cpp

@@ -35,6 +35,7 @@
 #include "terrain/terrCell.h"
 #include "terrain/terrCellMaterial.h"
 #include "math/util/matrixSet.h"
+#include "materials/materialManager.h"
 
 bool RenderTerrainMgr::smRenderWireframe = false;
 
@@ -117,6 +118,10 @@ void RenderTerrainMgr::render( SceneRenderState *state )
    if ( mInstVector.empty() )
       return;
 
+   // Check if bin is disabled in advanced lighting.
+   if ( MATMGR->getPrePassEnabled() && mBasicOnly )
+      return;
+
    PROFILE_SCOPE( RenderTerrainMgr_Render );
 
    GFXTransformSaver saver;