What do you wanna know? :P I use this little guy https://www.amazon.com/gp/product/B01DLPUWKI.
I've found a few reasons why it's necessary for me. I believe the high humidity is lowering the temperature in the greenhouse, as when it's high rh inside it's usually 5-10 degrees colder than outside at night. I don't know if the water is cooling the air somehow, but I've now confirmed this by leaving the dehuey off for a few days and during those days the temperature problem came back.
The DH also outputs a small amount of heat but doesn't really impact the overall temp in the greenhouse, though it can keep 1 plant next to it pretty warm.
I also grow cacti and they don't much like high humidity so thats another reason I use it. I'm also concerned that with high humidity I have more potential for frost damage if temps ever did get down to 32, which hopefully never happens in the greenhouse :P
edit: a note on the DH, it just barely is the right size for a 10x20. I had it for my indoor grow room originally where it works much better obviously. Outside at night it can struggle to fight the humidity, but it has an impact for sure. Also it looks like they did weird shit with the pricing on different models for tht unit since I bought it. The one I linked is definitely not the best deal atm (pint size/$)