In order to tack the thin backs to the Base Bottom and Base Rear Rail more efficiently, we've always moved our Nailers a little. I added globals:
Base Top Nailer Z Offset
Base Bottom Nailer Z Offset
Tall Top Nailer Z Offset
Tall Bottom Nailer Z Offset
Upper Top Nailer Z Offset
Upper Bottom Nailer Z Offset
Then I subtract INDIRECT("G!"&Product_Type&"_Top_Nailer_Z_Offset") from the Z Origin of all Top Nailers (similar with adding to bottom nailers) in Library Designer.