I think the easiest way would be to have a last will written that explicitly states who to contact and not contact.
If your body is at all found at any time, forensics obligate identification to rule out criminal deaths, and then standard procedure for the morticians or lawyers would be to contact closest family on how to proceed with funeral and potential inheritance, unless a last will says otherwise.
Now is it legal to have a "silent" funeral like you want, with no one involved in your country, I don't know that.
Other choice would be to ctb somewhere no one would not find you for a hundred years, or destruction of body after death.
They will take a dental imprint and pull dental records internationally to identify your person, and I just don't see how anyone could destroy their body enough before or after death to avoid that.
Sorry if that description is too grim.
I think what I'm trying to say is lawyer up and figure this out.
Sometimes it can be done online if that is easier for you to do.