Begin at the posted coordinates, where you will see a plaque in front of a tree. Ignore the Roman numerals. Look at the row of numbers, and count from left to right.
B = first number
C = fourth number
H = sixth number
Now proceed to stage 2 at N 37° 31.450 W 120° 51.241.
A = first letter of the first word in the top right corner
E = the number of letters in the word directly above "(FUTURE)"
G = first digit of the only year you see (read digits from left to right)
I = the last letter in the line below the map
Continue to stage 3 at N 37° 31.450 W 120° 51.248.
D = the number of picnic tables under the wiry green gazebo, multiplied by 2
F = the number of triangular windows in the roof of the Bio-Ag dome
J = the number of empty wooden planters in front of you
The final stage and the cache are located at N 37 AB.CDE,W 120 FG.HIJ.
You can validate your puzzle solution with certitude.