I will let others inform you on road issues - but the 173 route to the Bradford Ridge trail is only open from the south to my knowledge, from the Lake Arrowhead side. It is the route many from LA take. It does not require an FJ or a 4x4 vehicle as the whole way to the trailhead is paved.

Given that it is summer, I would not advise the Bradford Ridge route for a first time visit. The hike is longer - around 3 miles each way. And the trail blazes in the sun. And the climb back out of the creek basin is killer in hot temperatures. If you haven't been before, that is my advice.

In fact if you haven't been before, I would simply advise you go to Bowen Ranch and pay to park and camp there. It is convenient and safe and you can build knowledge of the trails and area. You should not camp at the creek. The law is to camp a mile away from the water. I have seen rangers ticket. It also contributes to trash and sanitation problems at the springs when people stay down there. Bowen has some good picnic tables and it is best to camp there I would think. Car camping possible as you can drive the car right to the camping spots. It is 5$ per person to park for the day, or if you stay overnight 10$ per person to camp for the 24 hours instead.

For the desert side routes to Bowen or the Freedom trail, it is good you have the FJ.