If you had two vents on each side and fans, you could do it, depending on your climate and sun exposure. Auto vents are most useful for when you are not home. I'd suggest access to a shaded pen in summer to get away from the heat of the day. I ran a set up like that with doves but I had to shade part of the greenhouse in summer and use blowers if the humidity got too high. In Virginia that might not be too bad, as it would be further south. You can always tarp or vine over parts of it if it gets too hot and too humid.
If you provide them some of their own plantings they don't try as hard to take out the plants higher up. I just rotate pots into their enclosure and out when they're stripped. Works for the parrots I have as well. Silkies wouldn't get as high, Seramas fly well and LOVE to get up high. Some plants tolerate attention from smaller chickens, some don't. Don't put anything in a greenhouse that is toxic, that includes most house plants, be careful. Many of the plants people use for flighted parrot enclosures work well with chickens. Many roses, tall grasses, many bamboos, several vines all do well once established.
It's best in a greenhouse set up to find a way to provide running water, cool water, always fresh, helps a great deal.