Clearly, the Air's limitations of storage space, connectivity, and rendering speed are not attractive to professional video editors under deadline. I'm just curious to know what is possible with a little time and ingenuity.
You pretty much know the figures now. It's for you to judge whether it's enough for your plans.
Two points: one, performance takes a significant hit when the drive approaches capacity; and two, you always need more (space, in this case) than you think.