It actually doesn't take as much liquid as you might think. I recently smoked up 40 lbs of pork shoulder for a church dinner, and the soaking stage only took 5 bottles of beer - which meant one left for the cook
. The trick is to use a narrow cooler so there is not a lot of room for the meat to spread out. That way the beer fills the gaps and gets all over the meat without having to fill a bunch of unnecessary space. Get it to the point where the beer just barely covers all the meat, and top it off with some ice to keep things nice and cold. It should be good for a 24 hour soak without having to mess with it. I usually pick up a cheap styrofoam cooler to do this in, by the way, so I don't have to worry about whether my good cooler is safe to put other food stuff in later on.