4-bar hinge technology is applied to forward hinged mounting of a conventional cab high cover on a pickup truck load bed, so that the cover moves clear of the vehicle cab when raised to provide improved loading access. The hinge system may be integrated with upper and/or lower rails intermediately attached to the cover and load bed rails used as mounting interfaces in fixed cover installations. Use of these interfaces alone for system attachment supports universal application to conventional matched cab high covers and load beds with minimal component variation between applications. Resulting component dimensions accommodate compact packaging, and therefore convenient, efficient shipping and storage of adaptation hardware. The system concept accommodates use of readily available hardware suited to processes and equipment already in use within affected industries, and facilitates capture of dimensions for optimal function within hinge and intermediate rail assemblies, thereby minimizing reliance upon installer skills.