Are there any active duty soldiers stationed at Camp Pendleton, CA or NAS in Pensacola?

No there are not. If you ever want to know about Army units you can look them up on FMSWEB. Even if there were you probably wouldn't get the assignment. Having your MOS at a location doesn't mean there are openings or that you can fill them. Just because you can request a location when it's time to reenlist, does not mean the strengths will support your request.

There are Army posts reasonably close to those locations. Fort Irwin and Fort Huachuca are the closest to San Diego. You probably won't get Huachuca, you can usually get Irwin. Eglin Air Force Base is the closest to NAS Pensacola. 7th SF Group is there and you can probably get that if you have a clearance, you're an American citizen, A GT of 100, and you're Airborne. Otherwise, Fort Rucker, Benning, and Polk are a few hours drive away.

It's been some years but they used to have cross training between the Army, and Marine Corp at Camp Pendleton, mind you that was in the late 70's, Pensacola would probably be your best bet though.

I am at Camp Pendleton as a Reservist and we have Active Guard Reserves (AGR) soldiers whom are title 10 active duty. Unless you go recruiting, AGR is your only way. There is a Civil Affairs Airborne unit in area 33 along with an MP unit in the same building.