Maybe we could chop the trees down and build homes out of them? Could help w/ California's homelessness problem...
I was going to suggest burying the wood, but my guess is this would just increase methane emission from microbes, which is far worse than the CO2 released by burning.
I think controlled burns are still the best option at the moment.
My intuition is that a city will be easiest to defend from fire if its area-to-perimeter ratio is low, i.e. it is big. For example, there is no real risk of San Jose burning down in a fire, because its area (square of the radius) means it has lots of water mains and firefighters, while its perimeter (linear in the radius) is comparatively defendable. That suggests the strategy of expanding existing forest cities.