World War II Letters - 31 October 1942 - Written by Stan Cooper

Stan sends the family $50 for Christmas to spend on themselves. He states he needs no money as he "is far west from Uncle Joe." That is Honolulu. I would say, farther "southwest!"

Since 15 June, the USS San Diego was one of the ships to escort the USS Hornet in the Pacific. Just five days previously, 26 October, the USS San Diego was involved with a battle with the Japanese, and witnessed the sinking of the USS Hornet.1 

Of course, he cannot mention any of this to his family. This identifies their location north of the Santa Cruz Islands in the Pacific. 

The Battle of the Santa Cruz Islands was intense with 136 
U.S. carrier aircraft including the USS San Diego, with the loss of 81 aircraft and 24 flight crew of whom four became prisoners of war.2 

1.  https://en.wikipedia.org/wiki/USS_San_Diego_(CL-53)
2.  The Loss of the USS Hornet.                  http://www.pacificwar.org.au/Guadalcanal/SantaCruz/LossofHornet.html