For a wide variety of works composed by a prominent Roman statesman, a good place to look is the works of Marcus Tullius Cicero (107-43 BC), a hugely influential lawyer, politician, rhetorician, and theorist of the late Roman Republic. His work is some of the best preserved of the period and it covers a whole host of topics. While he's more famous for his eventful political life (he was Consul in 63 and a whole lot more), he composed a large body of valuable philosophical work. As I'm more familiar with his political life I can't give any in-depth insights on his philosophy but I can point you some of his more prominent treatises. Try On the Laws or On the Republic.

I hope these provide something along the lines of what you were looking for. Cicero was very prolific so there's plenty to choose from. Also I apologize for linking only excerpts of On the Laws. Tracking down a full online version was harder than I thought.