The 126 is much improved since '92. It is wider, with 4 lanes in most places, and better marked in than it used to be. Personally I think it's an easy drive from Ventura to Santa Clarita and I do it rather often. Yes there can be fog, but that's coastal living! Personally I find driving at night more difficult than in fog. However, with safe driving you can count on a 1 hour to 1 1/4 hour commute each way.
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.