I'd assume wiring is the best option as well, regardless on if physically having that cash through borders is 'legal' it still looks incredibly suspicious and there will be a headache with customs and bureaucracy in this situation when time is of the essence and any hold-ups can't be afforded.
My uncle once had cigarettes he purchased abroad, within the legal limit for personal use, taken off him by customs because 'he didn't look or smell like a smoker' - well yeah he's been on trains and a plane all day did you expect him to spark up on an airplane just so he smells like a smoker when he passes through customs? He's been a 20+-a-day his entire life, he has absolutely zero intention of selling them but that's what customs believed so they confiscated them all. Customs agent was rude and aggressive so he terminated the interview so they took that as an admission of guilt, he appealed and took it to tribunal but they sided with customs. You cannot assume Customs Agents follow the law, you can go into months of fighting them in courts and still lose. It's sad and shouldn't be that way but that's the way it is currently and what we have to deal with.