We live in San Diego also. We started training in May for our Labor Day summit. I can only share what worked for us. To give this a little perspective I am 57 and my wife is 58, although we are really good physical shape. Sounds like your 7 mile – 1,900’ elevation hike is Mt. Woodson.
We started doing hikes on most weekends at Mt. Woodson and Iron Mountain. Days we couldn’t devote the time we would walk/run around Miramar Lake. We did two warm-up overnights since we hadn’t been backpacking in 20+ years. We also wanted to get some elevation to see if the Diamox would really work. BTW it did for us. The first overnight was one canyon south of Whitney at Muir Lake 11,500’ out of Horseshoe Meadows. The second a week before our summit was up to Kearsarge Pass ~12,000’ one canyon north of Whitney.
We did not do it in one day. We overnighted on the way up and after the summit. You’ll be fine! Good luck
