Oysters are notorious for needing tons of fresh air. The humidity is just to keep the caps from drying and cracking, and not an absolute hard requirement for development. If they are stunted, it’s the air. (I personally wouldn’t go without spraying or using a fogger, but it’s possible, is what I am saying.)
LC is the way to go if you feel like making the investment, especially for small growers like us. You need some jars and the proper lids. That is about it. I am doing a well rounded LC mix, but you can get away with just using corn syrup and water. You will probably need a pressure canner to sterilize the solution as pasteurization will not cut it. (I am sure there are methods out there that don’t use pressure canners, but I haven’t looked.)
For LC videos, there are tons of them out there. YouTube search for “Super Liquid Culture” or look through the videos by Mossy Creek Mushrooms for his formulas. At the end of the day, as long as the solution is clean and has sugar, the mycelium should eat it up. Malt and peptone are just helpful. In some cases, increased nutrients increase the risk of contam taking hold.