Cyanide

I would combine the two methods actually.

Many humis are constructed so the inner lining is a separate wood from the body (eg spanish cedar lined). I find many of those are fairly loosely put together. If so, you may wish to carefully remove the inserts, finely sand the inner-facing surfaces, air them out for awhile and put the baking soda in the rest of the humi. Then, reintroduce the liner wood and keep the baking soda in there for another week or so.

But, I wouldn't be surprised if this approach is well beyond "over the top"