How much head space was there?
Plenty - this wasn't a secndary. It was a primary. I only "secondary" in kegs. I prefer to call it bright tank though.
Kai - yeah, at the very least I would really worry about carboy breakage.
Blatz - What the hell, man, my wife can't lift a full carboy!!! To be honest, it isn't really that bad yet. Drink it quick and keep it cold. Won't be sending it out though. Plus, my wife probably won't bat an eye while she drinks it. I mostly brew kolsch for her... mostly.
As far as the dry air lock there was an article how to make one in BYO a few years ago with McMasterCarr parts. I'll see if I can find it. Still, nothing beats stainless under pressure.