Dave, a couple questions/thoughts:
1. What percentage of the sunlight do you think gets through that roof?
2. When you bring them out after they've leafed out so much, do they get sunburn? If not, I'd say it's a great way to get a headstart on the season.
3. When I start my tomatoes indoors, I turn a fan on them to simulate wind for a couple weeks before I set them out. Maybe you'd want to do this for your fig trees?