re: Suggestion
Well my suggestion was in jest and yours (of overalls) is probably the most workable. It doesn't more personal ways of smuggling explosives in that have been used for decades by the drug trade. Depends also on how much explosives you need to knock a small hole in a plane for it to depressurize vs. how much you would need to cause structural damage to cause it to crash.
Quite a problem - another suggestion I heard is to just knock everyone out and put them into small tubes and stack'm up and ship'm.