No person may clone or attempt to clone a human being.
"Clone or attempt to clone a human being” means to implant in a uterus or attempt to implant in a uterus anything other than the product of fertilization of an egg of a human female by a sperm of a human male for the purpose of initiating a pregnancy that could result in the creation of a human fetus, or the birth of a human being.
Of course, it is also a very useless egg and sperm law, as all it does is prohibit the actual implantation, presumably within the borders of Missouri. It does not say what would happen if a Missouri lab created the embryo with Missouri money, Missouri researchers, and Missouri progenators, but they simply drove to Illinois to perform the implantation. It doesn't look like that would break the law.
We need a Federal egg and sperm law, and it has to prohibit more than just implantation. It has to prohibit the conception of children from anything other than a man's sperm and a woman's egg, and I mean conception in the most conceptual meaning conceivable. It has to rule out the very idea of a person that isn't the union of a man and a woman's gametes, and prohibit people from attempting realize that idea no matter what country they plan on doing it in. And it has to have no statute of limitations, it has to be enforceable when any of the parties involved in the attempt return to US soil. (The person created is not a party to the attempt, obviously. But the progenators, the scientists, and the owners of the lab would all be guilty and subject to fines and imprisonment).
Other countries would surely follow in enacting egg and sperm laws, and the UN is already way ahead on this issue, with both a cloning ban (that the US has not ratified) and a declaration of the rights of children (that the US has not ratified). If there is some Island of Dr. Sullivan where same-sex couples can conceive children, they will have to live the rest of their lives there.