Initial Solution: AltB select the camera boundary. Pro: Simple Con: Limited view of other references.
Alternative Solution: Vertex/ Face Mask. Pro: Flexibility & control Con: N/A. 
Most Efficient Solution: Adjust Mesh to Camera View. Pro: No wasted vertices Con: Camera is set - less flexible. 
Initial Solution: AltB select the camera boundary. Pro: Simple Con: Limited view of other references.
Alternative Solution: Vertex/ Face Mask. Pro: Flexibility & control Con: N/A.
Most Efficient Solution: Adjust Mesh to Camera View. Pro: No wasted vertices Con: Camera is set - less flexible.
Initial Solution: AltB select the camera boundary. Pro: Simple Con: Limited view of other references.
Alternative Solution: Vertex/ Face Mask. Pro: Flexibility & control Con: N/A.
Most Efficient Solution: Adjust Mesh to Camera View. Pro: No wasted vertices Con: Camera is set - less flexible.
Perhaps an easy option is to go into camera view and andInitial Solution: AltB select the camera boundary. When you go into weight paint mode you have the exact borderPro: Simple Con: Limited view of what is visible to paintother references.
AltB again to returnAlternative Solution: Vertex/ Face Mask. Pro: Flexibility & control Con: N/A.
Most Efficient Solution: Adjust Mesh to full viewCamera View. Pro: No wasted vertices Con: Camera is set - less flexible.
Perhaps an easy option is to go into camera view and and AltB select the camera boundary. When you go into weight paint mode you have the exact border of what is visible to paint. AltB again to return to full view.
Initial Solution: AltB select the camera boundary. Pro: Simple Con: Limited view of other references.
Alternative Solution: Vertex/ Face Mask. Pro: Flexibility & control Con: N/A.
Most Efficient Solution: Adjust Mesh to Camera View. Pro: No wasted vertices Con: Camera is set - less flexible.
