It seems putting in wide, permanent fire breaks in these areas, particularly around inhabited areas, would stop fires
from spreading.
Not when these winds kick up. There's not a firebreak in the word that will stop the embers from traveling in hurricane force gusts.
Would have no effect in this situation. The Santa Ana winds are just too strong and the area too dry. Even if there were huge firebreaks, the winds would blow the embers past the firebreaks and into the next forested/flammable area. And the fires aren’t arson, they’re electrical fires started from power-lines that have been knocked down by the winds. The only hope for the area is that the winds will die down. And pray.
An interstate highway, including the total width of its easement, is about 10X wider than any common firebreak, ad it didn’t stop this monster.
So, what would you suggest, denuding a mile-wide swath of Earth?
Have you thought about how you might address the soil erosion issues involved with having so much bare dirt; both by water and wind?
Not to be harsh, just to point out that these things are more complex than they seem to be, and, quite often, solutions come with their own set of new problems. If we’re lucky, the ratio is 1:1 and we trade a difficult problem for an easier one. Most of the time, we’re not that lucky.