The Mackmyra whiskey distillery in Gavle, Sweden is currently constructing a gravity flow distillery. It will be the first of its kind. I pulled a couple links for you. There isn't much technical information, but at least you know the concept can be done, and there's possibly someone you can talk to about it.
http://pondsthlm.com/whisky-engineered-by-nature/
You'll have to translate this into English. It gives general information about the plant design.
http://www.mackmyra.se/content/besoek/mackmyra_whiskyby/?p=Gravitationsdestilleriet
Basically, it's similar to what you have in mind. I think it's an intriguing idea. Good luck!
-Eric