Is it really so easy to hide it from all the relevant people, including close friends and relatives, let alone significant others (who, according to what I've read about the topic, usually are the most powerful obstacle)?

Also, I'm not very knowledgeable about this sort of thing, but it seems to me like doing it completely in secret could endanger the success of the procedure after your death. Imagine if a bereaved family and/or spouse suddenly find out that their beloved deceased has requested this terrible and obscene thing instead of a proper funeral, which not only shocks them, but also raises the frightening possibility that once the word spreads, they'll also be tainted with this awful association in people's minds. I wouldn't be surprised if they fight tooth and nail to prevent the cryonics people from taking possession of the body, though I don't know what realistic chances of success they might have (which probably depends on the local laws).

(I wonder if some people around here actually know of real-life stories of this kind and how they tend to play out? I'm sure at least some have happened in practice.)