What you describe is essentially the program they had in place already. Maybe not 120 feet, but certainly some distance. They hire contract helicopters year round to survey lines, and task crews to clear brush. I live in Sonoma County, CA [1,2,3] - so we see the effort.
I think you might also be underestimating the scale of the power infrastructure in CA. The hydro etc. power generators in the north of the state are located in extremely remote areas.
My brother was a consulting engineer for PG&E in Northern CA, on a lot of their Hydropower infrastructure - most of the generation sites were only accessible by humans with helicopter flights, or 2-3 hr drives on poorly maintained roads. The transmission lines are not really accessible except by helicopter survey.
1 - https://en.wikipedia.org/wiki/LNU_Lightning_Complex_fires