Off the top of my head I would say to try the command `split`. It allows you to break a file into chunks with a megabyte option. Might try something like :

Of course, this only works if the tar is on a filesystem and not on tape.

Of course, after I posted this response I got to thinking: "How would I recombine that split parts?" That's a good question and I am thinking about it..

Hmmmm.....

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