I started taking this to work as a way to use up frozen shrimp and "crab". Turns out it was awesome and everyone who saw me putting this together, wanted to know what was in it so they could make their own!
If packing this for lunch, pack all ingredients separately. Put the lettuce in a large zippy bag. Put the frozen shrimp in their own small zippy bag, then put that in the lettuce bag. They will help keep the lettuce nice & crispy, and should thaw out by lunch time. (If they're still frozen, you can run their bag under cold running water for a few minutes and that should do the trick). Do the same with all the other ingredients.
When it's time for lunch, just dump all the small bags of ingredients into the lettuce bag, add the dressing, zip it up & toss right in the bag. Then you can dump it out into your plate/bowl and get to the eatin'. :)