Report: Really enjoyed this route. I wanted to start as soon as there was light, which was maybe 30 minutes before when I actually started but no big deal. The first 10 miles felt really good, temperature was nice, and the sun was blocked by the hills. Once I got near the lake and the slightly more technical parts I started slowing down. For a while after the lake there isn't really any shade, and the sun was definitely up the heatwave was in full effect. When I got to the flooded road (that it seems everyone has encountered, maybe this road is just permanently flooded) I really needed the water so I soaked my clothes and filled my bladder. Water tasted like it came from a hose so I just crossed my fingers that it wouldn't kill me. Following Kipley's route I went around the private property (I want to say it was a horse ranch?) and through the golf course (which also had private property signs but the trail was obviously not created by this golf course and nobody seemed to care). I found another small creek and refilled on cool water. The rest of the route was pretty smooth to the finish which was good because I was pretty beat. Over all this route was awesome.
Other thoughts: I think Kipley was right with recommending that the start follow the trail instead of the road. The trail has signs and looks well-established and this wouldn't change the distance much, if at all. For the private property (house) right after the switchbacks at mile 23, the detour Kipley took and I followed was via a service road so that's definitely a kosher route. THE FINISH I propose should be very slightly changed so that it ends with your feet in the water at Powerhouse beach. This would add about 0.1 miles to the route but would give it some good finality and since the route follows the "Coast" to Crest trail it seems fitting.
Shout out to Steve, Allen and especially Kipley for working on this route before. I'll do a better write up as soon as I can at https://rowdyrunning.com/fkt-san-dieguito-coast-to-crest-trail/