not sure about your regs now but it used to be the case and i would think still is that you cannot throw anything out of an aircraft ( helicopter)...without the permission of the minister.
that said it is often done since it is not ( if you like ) siomething likely to cause damage nor injure.
can't help about the blowback as i dont drive choppers but i would expect it.
we had one person years back...who not thinking what he was doing threw THE URN out from the back of a cessna 206...and it hit the tail !!
..and put a huge dent in it ...and could well have taken the tail off..
so all things considered..its a thoughtful idea but maybe it would be just as nice to scatter from a cliff into the ocean ( though not a sailor ) or from a mountain top...and avoid any problems..
i would regard the ocean clifftop as symbolic of the free spirit of the pilot still travelling the globe..but maybe you are a long way from the ocean..
anyway..good luck.