I don't know how you feel about bean dip, but the lady over at Vegan Lunch Box (http://www.veganlunchbox.com) was having the same problem, and apparently the way she was able to pack avocado was in making it like, the third or fourth layer of bean dip, which also prevented it from going brown.

Avocado is one of those things I just cannot eat unless I travel, because by the time avocados get to Tennessee they are already pretty gross. It makes me sad because they are so verra verra good for you, but when they are already hella nasty by the time you buy them it's just not worth it.