@Iowacountryboy this is a very good use of space. The lower humidity will be helpful during flowering. Lower the better. Veg you can get by at 40% you may have to water a bit more often. (But don’t do it too much check the soil first) Make sure you have holes in your solo cups so the water can drain. I know I’m jumping ahead but do you have something to transplant to from the solo cups? If so, what size? I think as long as you keep air moving you should be fine. When it comes to spring air exchange might more critical to keep the mold issue at bay. If it is a problem. Some spaces are fine.
Do you have enough lighting?
And of course welcome to the forum. This place is great and filled with many helpful members here. We all want you to succeed, from seed to harvest. Happy growing. Don’t forget, when responding don’t forget to put @covertgrower so we get notified.