What is the proper use of "thereby" when involving a copula?

I am worried about splitting up linking verbs when using “thereby” or “therefore”. I am probably being hung up on the “by” in thereby, however.

“It would thereby be worthwhile” – sounds fine, but splits up “would be”

“It would be thereby worthwhile” – sounds worse, but does not split up the copula “would be”

Which one would be more grammatically correct? Furthermore, is it considered in bad taste to even use the word in such a sentence, given it is entirely inessential?