There are two Navy Military RV parks in San Diego. I'm not sure how long you can stay in them but I believe they will allow active duty people to stay a little longer. Each military RV park has its own rules about length of stay. In San Diego there is the Admiral Baker RV Park and the newly built Fiddler's Cove RV Park. And just north of San Diego there are three military RV parks on Camp Pendleton.
We have stayed at Admiral Baker RV Park and I have talked to active duty Navy personnel that were living there.
I have never worried about safety in San Diego. That said, I believe both RV parks in San Diego do not have controlled access. Camp Pendelton, on the other hand, has controlled access.
There is also a Navy Weapons Station in LA with an RV park about 15 miles from Disneyland and about 30 miles from Universal Studios. It also has controlled access. A nice place to go for a weekend stay.
I don't think the RV parks in San Diego has storage facilities. I suspect the Navy has storage facilities somewhere in San Diego.
Here is a link to Military Camping: http://www.militarycampgrounds.us/
Safe travels.
JD