ORIGINAL: BMatthews
The picture tells a 1000 words and those words are saying "THEY ARE NUTS! ! !". You're right to question that location. I don't know where they got that number but it would be a disaster looking for a place close by to happen at takeoff time. I'd go with 1.7 to 1.75 from the upper leading edge and see how it works out for the test flight. That would be a safe starting point for sure.
Gotta agree there. Whatever CG the OP decides, I think he's very wise to question that 3.5" measurement...it looks light years too far rearward.