No, you dropped the ball. No one writes a kesuba without the intent to consume it with the maaisa. Who are you kidding? If they write the kesuba, they are doing the maaisa.
So the two possibilities are either the mishkav zochorniks doing the maaisa with a kesuba or without a kesuba. If we could outlaw and otherwise stop them from doing the maaisa altogether, we by all means should work on accomplishing that very worthwhile goal. (And it should be note that, in fact, the maaisa itself was illegal in the United States until in the not too distant past. So it isn’t only a pipe dream.) But considering that writing the kesuba on top of the maaisa makes it that much worse (as we all agree), we should certainly at least work against letting it advance that far (i.e. with a kesuba).
And that is exactly what we see the Gedolim shlita advocating, as we saw above from Rav Shmuel shlita.