Second what others have said. The Tom Harrison map is perfect, because it has elevations of key points on the trail and the distances between them. You can find it at any of the REI’s in the San Diego area. There is also a digital version. It works with the free Avenza app, and is available for both iPhones and Androids. I recommend the digital version for cross-country and snow trips, because you can locate yourself quickly on the map, but it is not necessary for trail hiking.
The Vivian Creek camp area is low compared to Halfway Camp and High Creek, but has advantages: roomy, shady, and water right there. Makes sense for the three day trip from San Diego you outlined. But the mosquitos can be bad in the evening! I would take mosquito repellant, and suitable mosquito-proof clothing.