Best wishes for success and no more rot ever. Gardening is an art that takes practice.

Noah, I have to question why you are using a greenhouse at all where you live? I have seen your pictures, and it looks like you are using a store bought green house with a plastic cover? Those have no ventilation, to my knowledge, and if you keep the doors shut all the time, the humidity inside will go through the roof causing all these problems that you post about. I've never been to Texas, but I've heard the summers can be brutal, so why not have your plants outside with a shade cloth to use, as necessary? The air circulation would no longer be a problem.

Nancy

So open the doors and put a Shade on

Remove the plastic covering and use shade cloth

Here is a link that might be useful: Example