I think it can be done. In a Roman Republic mod, you would play as a Roman patrician family. Although there were more than five patrician families, there were gentes maiores and gentes minores. Gentes maiores were only six: Julia , Aemilia, Cornelia, Fabia, Manlia and Valeria. There could rise other families in place of another, of course. Like the DLC, there would be elections for two consulate places each year. After your term as consul expires, you could be made a proconsul (governor of a province, like Caesar in Gaul) and make conquests. Patricians in ancient Rome did not take part actively in trade, as it was considered indecent of them, but they had clientes who carried throught the job in their service. I think it is possible, although a lot of work would need to be put.