That sounds reasonable. I presumed that you knew for sure your Schmidt
was born in Mecklenburg. I find the Johann Joachim name fascinating. And
here again, family naming patterns are imortant. Was he known by Joachim or
Johann? The reason I ask that is that it would be far easier to search for
Joachim than Johann! You might want to run a search on the website below
(if you haven't already) for Johann Joachim Schmidt (or just Joachim) and
you will see a Mecklenburg birthplace. Rohlstorf is in Mecklenburg and the
LDS would have the film, but since the name Schmidt is so common a name,
that may be a real long shot.
Google searches with Joachim Schmidt (with quotes) or with Johann Joachim
Schmidt also can be helpful. Variations of that also on the LDS site may be
interesting as well. Do you know his birthdate?
It would be so nice if you could find the passenger list and if Sophie came
with him, then it would be more likely that she lived very near to him. I
know you know all that, but we have to think of every angle!