I biked that route and that direction a year ago exactly. Not as dangerous as you're thinking. In fact, that 3rd picture I actually remember being at that point! I biked southern CA for 13 weeks last winter and was very impressed and pleased with how safe the drivers were around me! I went south along the coast from Oceanside to the border and when I got back to Oceanside weeks later, then went north along the coast. LA County was the exception, of course.