I came across this sentence in Plato (Symposium 206c):
τίκτειν δὲ ἐν μὲν αἰσχρῷ οὐ δύναται, ἐν δὲ τῷ καλῷ.
And it cannot beget on the ugly, but on the beautiful.
This μέν...δέ sentence omits the verb (δύναται) in the second part of the sentence and uses δέ to make up for it. So your third example sentence, with a non-final δέ, seems to be permitted in ...