one important issue to take into consideration is that in real life, sometimes things are not as advertised, ie if you arrive at the airport and Joe-Blow on the phone told you the day before that, "sure, we have boxes/bags" and then you arrive there and no one can find them, well thats a problem.
Yeah, that can be an issue. I mitigated that last time by getting the box the night before leaving (as we were staying in an airport hotel).
This time, I'll probably verify they have them before I leave the airport. Worst case, I go to a home improvement shop and get some plastic sheeting, and make my own. Also gave half a thought to just taking an old mattress one I have, rolling it up, and ziptying it to the underside of my rack so I have it for sure.