While there I lived in Santa Barbara and Ventura. In my opinion, Oxnard is a PIT. I would not live there if the house was free. Dirty and crowded with nasty people and box stores as far as the eye can see. Terrible food and nightlife. The beaches are awful in terms of surf and the water is freezing. Add on a 45 minute (!!) commute and you basically have a recipe for disaster.
Traffic is awful as well, with slow going either north or south from there. Try to get to Santa Barbara and end up in traffic. Try to get to LA and plan on spending 2 hours in the car no matter the time you go.
My advice is run far away from there. Buy a place in LA. It may be more expensive, but at least you won't blow your brains out after a year
The only objective way to evaluate a road's danger or safety is to look at the statistics of accidents or fatalities per mile of road compared to your other commuting options. I think you'll find that the 126 is not that bad. I would suggest looking to Caltrans or the CHP for these if you're really concerned about it.
Oxnard is an interesting place to live. It really depends on where in Oxnard you are. There are some really nice houses and neighborhoods down by the Silver Strand/Hollywood Beach, Oxnard Beach/Mandalay, and Pt. Hueneme areas, as well as by the River Ridge Golf course - but there are some pretty lousy areas that are typically in the inland central and east sides. Also the areas that are bordered by farms may seem romantic at first, but they really stink when they fertilize the fields and there is a substantial amount of industry that is not pleasant on the eyes or ears that is to be avoided as well.
Like any town, it has variety and you'll have to check it out before moving. Personally, I find Ventura to be a much better place to live - and bought accordingly.
As to the distance ... only can decide what your confortable with. I knew of people that lived in Ontario, Rancho Cucamonga, etc, that drove into Glendale (by Dodger Stadium) every day. They would leave home at 5:30AM, to beat the traffic, and get to the office at 6:30. If they waited untill 6 to leave they wouldn't get in until 8. Distance in So Cal doesn't seem to mean much, but TIME in the car.
I can't answer the question on Oxnard as I know that market has changed considerably since I was there. You might consider Camarillo? Still relatively close to the beach weather but an easier drive for your wife and more options for you to drive to SC.