According to certain embodiments, a vibration-isolating system comprises a platform adapted to carry one or more loads and an adjustable load-positioning system. The platform is suspended within a support structure by a plurality of isolators. The isolators are tuned to impede vibrations in a pre-determined frequency range for a payload having a pre-determined mass. The adjustable load-positioning system is adapted to facilitate positioning the one or more loads such that the payload having the pre-determined mass is centered at the center of gravity of the platform.