to be honest though even if they are packed your going to save time over hand methods, so the time you save use that on clearing up, and if you can have a kid working with you to clear up, will will prob earn out of the job and have free equipment
did i similar thing a few years ago except with decorating, time to complete job was 6weeks with a roller, we bought a spray machine and did it in 2weeks, and still had loads left over and a great piece of kit which has paid for its self again and again