Where are you mounting the faucets, in a collar or up on a tower? If you mount in a collar, you're going to need more than 5'. It will be more like 8-9 in my opinion. Because it's so much cheaper to buy 10 foot runs than going with 5 first and finding out you really needed 7, just buy 10 and start there.
Don't forget, you'll need a temp controller if you use a freezer.