I also don't want to be found, and have been thinking about how for a very long time.
My conclusion is that if you can get to that remote area of a forest or mountain, so can hikers... and they eventually will. I don't want to (ever) be found, so that thought scares me. In my opinion, the safest way to do that in a remote area is to have someone along who can hide your remains, but I've never found anyone willing to do that. If you don't care if you're found quite a bit later, though, a remote area may very well work for you.
I never thought about the volcano idea, probably because we don't really have them in my part of the world, but I always imagined they would have people watching them pretty often. Are there active volcanoes out there that are completely unattended?