Pull the meter ( very high chance you don't have a meter based disconnect) Anti-Ox the mains, use the lower neutral bar and spread out the bunched up neutrals the right side and call it a day. You go any farther and you open up a rats nest. Spend the time and make it neat. You still may be bunched up because of lack of wire length. Having a sparky do it would cost you about $400+, but then you are documented. Because technically, depending on your state/city, because you are selling it, it is not your house. You don't have the "owners right to do licensed electrical work as long as it is permitted and passed- exemption" in the state/city's eyes. So you need a licensed tradesman to do the work. (cough)