You are in the San Luis Rey River valley. You can park right near the cache. There's lots of traffic in the afternoon, so you might have to wait a while to get back on the road.
This is a Special High Intensity Training cache to get you prepared for those D/T 3 or higher caches, power trails, and completing difficult challenges. You might find this one, but will you know you found it and be willing to pick it up and sign the log?