When bulk mushroom growers need an awesome medium for large tub grows, they usually use half/half Coco and vermiculite, pasteurized, then innoculated and left to sit for a few weeks. When you come back, the trays are fully colonized with fungus, they love Coco.
I did the same thing more or less with a fabric pot once, pasteurized it then used a myco product to innoculated, left it alone for a few weeks, then planted. With just some ewc and tea, I harvested nearly a pound of hot chilies under a single COB LED in a 2x2' tent. If you get the herd right and let it innoculated thoroughly, it's a hell of a living medium.
I also had a huge flush of Leucocoprinus Birnbaumii show up in an outdoor planting of ghost peppers that were in 100% pure Coco, the stuff just wants to form mycorrhizae for you!