Straw as storage substrate in moist root cellar for onions?

I finally have a root cellar and I'm over the moon about it!
Humidity is really nice around 90-95%.

Now I have a several buckets of onions that I have a hard time storing in my tiny 200 square foot house. Unless I sleep on top of them.

Can they be kept in the admittedly too damp root cellar if I bury them in sawdust or cut-up straw?

Your root cellar looks great and made my wonder if I could build one somewhere in the garden.
I have no experience with storing things in a root cellar but high moisture and organic matter sounds like a dangerous environment for onions to me. They might mold or try to sprout. What I know about onions is to keep them dry.
I have heard of people storing stuff in ash. Would that maybe be a possibility?