Your c.g. is roughly where your hips are when you are in the leaning-back seating position. So if you measure where your hips are relative to the seat back, you can work out how far your c.g. is from the L/E.
You'll find your c.g. is very close to the aircraft's overall c.g., so the arm is small. This is one reason why the Max feels so great to fly: you are right at the centre of everything.
After much research on the subject check out NASA center of mass of the human body. Fat or thin, tall or short, vertical or prone, sitting with legs extended and arms extended (as in MiniMax) human body CG stays within one inch of the bellybutton.