A system configured in accordance with a particular embodiment includes a paint-striping machine having a carriage, an outrigger operably connected to the carriage, and a downwardly oriented nozzle carried by the outrigger. The carriage moves along pavement while the nozzle dispenses paint, thereby forming a paint stripe on the pavement. The system further includes a guidance system operably connected to the paint-striping machine. The guidance system includes a light-emitting device and a mounting and containment assembly that provides an adjustable connection between the light-emitting device and the paint-striping machine. The light-emitting device forms a planar light region having a vertical orientation. The mounting and containment assembly includes an adjustment mechanism operable to move the light-emitting device relative to the paint-striping machine, thereby changing a yaw angle of the planar light region.