STAGE 1, A VIRTUAL STAGE. Park here and position yourself at these coordinates. The 4-digit number you seek will be at compass heading 71 Deg at a distance of 160 feet.
The number is a clearly visible sign, WHITE with black numerals, posted a few feet above the ground. Just for fun, bring binoculars along and try to locate without moving from the waypoint. [added detail. There are actually TWO numbered signs like this. You seek the one that is further EAST. ] Do you have the right one? If you add the first 2 digits they = 10, then you have the right one.
SOLVE THE PUZZLE. Go back to your car parked at the Stage 1 waypoint. Using the number on the WHITE sign,
A = [first digit + third digit]
B = fourth digit
Final Physical coordinates are
N 28 41.4A8 W 081 50.B32