A representative spacecraft system includes a launch vehicle elongated along a launch vehicle axis and having at least one stage carrying a corresponding rocket engine. The representative system further includes an annular support structure carried by the at least one stage and positioned to support a cargo spacecraft having a service module and a cargo module. The cargo module of the cargo spacecraft is positioned along the launch vehicle axis in a direction distal from the support structure, and at least a portion of the service module of the cargo spacecraft positioned within an annulus of the support structure.