Commissioned to build a row of lights, want to make sure I'm doing it right/ no easier way
Just a possible alternative, if I read you right the conduit bodies in the box are out of sight.  Mount a piece of unistrut on the back wall of your box, and clamp the rigid pipes to the unistrut with strut clamps.  

Put a 5' wireway in the box fastened to the base or back of the box.  The pipes will come in the top of the wireway.  



You should really consider using low voltage lights, this just makes everything safer and gives you much more flexibility.  You can find low voltage lamps that will fit the Edison base, or just use a different base.  You could do this without the wireway if you were so inclined - just splice the 12V wires in your wooden box.  You could epoxy the sockets in the black pipe if so inclined.  You could use actual black pipe with floor flanges.