Very intriguing story, indeed. Younger sons of important noble houses coming to America are not at all unknown. I believe there was a Hohenzollern that did so.
If your ancestor were truly in a "royal" house, your search is limited. [Of course, Baden, while sovereign, was only made "royal" rather recently.] I just briefly scanned through the house of Baden entries in the online Gotha, looking for brothers born around the time you suggest. No luck. It occurs to me that "Albert" and "Joseph" may have been "Rufnamen" and not the first in the sometimes agonizingly long lists of given names, especially in royal families.
Were your ancestors from non-royal, but families of the highest nobility, your search becomes instantly more elaborate. I would focus first, of course, on such families seated in Baden. But, I'm not sure any list of "Fürstlich," say, families would readily give you their home territories. It could turn out to be quite a job, unless you are familiar with the materials and history.
Have you looked for newspaper accounts of the weddings in Holly Springs? I wonder if there were some enterprise that brought Germans to that town ... some connection. In that regard, I am thinking of my great grandfather, who found a position with the zinc rolling mills, in La Salle, Illinois, that were owned and operated by German immigrants. Another great grandfather, early upon arrival, here, worked on the Eads Bridge, St. Louis. For some reason, I believe that project's engineering was in charge of a German; and, likely, word got back to the technical high school, where my grt. grdfthr was studying.
Best of luck with your searches. I hope that if you, or anyone else, finds anything on this, that the results will find their way onto this list. Thank you.