Hi, welcome to the community, and thanks for sharing your question! There is currently not a way to extend crossfade to the extent you've mentioned, but please feel free to submit an idea here, and you might also have a look at this idea for a DJ version of Spotify. Although the idea is marked as "not right now," the Spotify team will certainly continue to monitor feedback, and there is some recommended DJ software on that page that perhaps would be worth looking into.
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