Hi Vagabond.. welcome on board. I do not operate under US regulations and customs, but perhaps your DOD would be the best port of call for advice on shipping in a PSK, if you are under contract to them. If they are expecting you to operate in a risky environment would they not provide ways and means to enable you to be suitably equipped? Would this not come under duty of care law?
In your shoes I would be suggesting they transport your sharps etc via military/diplomatic channels. After all, they have had plenty of practice at it...!!!
Cheers, PeterR, Australia.