I biked from home to the beach to start an unsupported / solo trek from the Pacific to Santiago peak. I carried all my nutrition with me and stopped for water resupply in O'Neill Regional Park (~half way time-wise). I don't have a water filter, but would consider getting and using one if doing a longer trek through this area this again (O'Niell water does not taste good). I followed Evan's suggestion to cross the Del Obispo Bridge in lieu of the street crossing. I missed a turn in O'Neill so ended up following a little loop, adding a little over a quarter mile. Fortunately it started to cool down a bit on the trek back down to my ride at Trabuco Creek Road, otherwise would have been out of water (water filter would have come in handy around Old Camp)! Thank you to Evan for outlining the route - it is fascinating you can go all the way from the ocean to Saddleback touching so little pavement - great experience!