Step 1: Concept
The sum of the distances of any point on an ellipse from its foci is constant and equal to the length of the major axis ($2a$).
Step 2: Analysis
Divide by 144 to get the standard form: $\frac{(x+2)^2}{36} + \frac{(y-4)^2}{16} = 1$.
Here $a^2 = 36 \implies a = 6$.
Step 3: Calculation
$F_1P + F_2P = 2a = 2(6) = 12$.
Final Answer: (B)