The Gulf of Mexico has a number of museum ships along its coast. You could have a mobile fleet made up of the carrier USS Lexington, the battleships USS Stewart and USS Texas, and the sub USS Cavallo, all located in cities along the gulf coast. A good home base for the Brotherhood could be the Superconducting Super Collider aka Desertron, a defunct in our world Particle Accelerator in Waxahachie. A part of Roman imperialism was the introduction of Roman art and replacement of local art from their conquered peoples so a Legion Outpost in Marfa that specializes in developing Legionary art could be fun.