Freeze drying is seems to be the best method for preservation of mushroom contents and the process is very simple:

1) freeze mushroom fruits
2) put frozen fruits in a box with a plenty of dessicant (e.g. silicagel)
3) apply vacuum
4) put the box in a freezer
5) after a day or two, move the dried fruits in a plastic bag and vacuum seal

The kitchen vacuum pump can produce about -80 kPa which is far cry from lab-grade lyophilization (this requires preparation, deeper pre-freezing and much higher vacuum). However, since ice sublimes at below-freezing-point temperatures anyway (though slower), the process may still "beat" the simple air drying, where heat, moisture and oxygen are present.

I plan to try the drying process on some champignons. The drying performance will be measured comparatively by weight loss (low temp oven with fan / air / freeze-dry).

Do you think the method would work? I have seen this working well for apples, so shrooms may not be an exception.