There is divided opinion about using a single wire of the data pair versus using both wires.
I'm of the single wire mind. Someone with a data probe could definitively answer that question.
Also, in your drawing, I don't see a black line (-5vdc) going between the two 5vdc power supplies. That is helpful/required to keep Data voltage stable.
A uAmp is better than a null pixel because it uses a better driver with higher slew rates to give a better output waveform.
But, null pixels are perhaps easier to find. Many controllers will let you treat a "regular pixel" as a null pixel.
Use shielded twisted pair cable to reduce capacitive loss to ground (could be a single pair or CAT5's four pairs)
Use Coax cable (great distance but not cheap per foot - you might have some lying around, though)
Get a Falcon F16v2 and use a Differential setup for that long distance stuff (you want one, anyway, right?