We're also wanting this mainly for overwintering stuff and seed starting. This past year we had so many trays of seedlings that we didn't have room in the house under the grow lights. That was a real wake up call for me!
I'm planning one interior door that goes into my shop, and at least one exterior door so I can enter the greenhouse from the outside. I may indeed have 2 exterior doors like you're doing. The dutch doors sound like a great idea. We have those at our barn and I love being able to keep just the top half open for airflow.
