I think there are some other wintersowers who put their containers in unheated greenhouses. I would think the greenhouse would act like a container so you might not even need to have them covered. But you're probably right that watering would be the biggest issue -- the pots in my garden window dry out very quickly.

I would think you would need to more closely monitor the moisture levels and make sure it is not too warm in the greenhouse. I would try to make sure it is very well vented. If it is kept too warm they will sprout earlier, be more susceptible to cold snaps, may need to be hardened off, or may even fry on warm sunny days.