Actually, that plan might benefit you in several ways...
You'd arrive to the Safari Park a bit later (11 - 12, as you mentioned); but that's OK because you'd be staying later to see the Jack-o-Lanterns. It would be a little busier, but like I mentioned, the Safari Park is pretty spread out, so it never really feels packed/crowded. Take your time and see everything, do the basic tram safari, etc. Then yes, I would go grab some dinner somewhere and come back for the lanterns. The only Sunday that might be bad would be the Columbus Day weekend....you haven't mentioned what weekend in October you're planning on.
By the time you leave Escondido to head to Newport, it will be later in the evening, which means the bulk of the 5 traffic will be gone....Sunday afternoons are the worst because people are heading home from weekend excursions...but by the evening, it will be better. You're probably looking at 1-2 hours from Escondido to Newport Beach. In the afternoon with heavy traffic, it could be 2 - 3!
Benefits:
You could start the morning later, getting some rest from so much driving.
See the Safari Park, with a nice dinner break...so might not be too long of a day.
See the lanterns and head to Newport Beach in the evening with a little less traffic, etc.