Thanks, BHDBOY, that's what I need to know -- that a "rule of reason" applies to this! It seems like if I comply within the spirit (but not the letter) of the carry-on restriction -- and don't bring ANY addition item -- I'll be OK.

BTW, I was looking at RyanAir's website, and they seem much stricter about carry-on -- such that nobody with a "normal" amount of luggage could comply (and avoid checking a bag). Is that applied in practice?