I'm now fairly certain that simple air drying should be avoided. Also, avoiding light is important.

Attaching a paper that discusses the subject. Interestingly, the found that N2 drying was superior to vacuum drying. However, they do not spell out their vacuum drying technique. One question is, if the vacuum chamber atmosphere is purged first with N2 or CO2, will vacuum be my just as good as drying over N2?

One interest thing is that they found vitamin C protected the product during vacuum dry and storage (see plots below). Another interesting thing is that they used ethyl acetate (available in the US hardware stores as MEK substitute) and ammonia to elute psilocin. We can try this on the cation resin which may give a purer product. Why? Because ethyl acetate is a protein crashing solvent, so it should leave proteins behind.

More stuff to consider. Work is ongoing