Kits provide management of implantable lead extensions being implanted by providing a kit body with features that retain the extension in a configuration, with amounts being removed as needed during the implantation procedure. The kit can be present within a sterile field, and the kit body features may be arranged so that a length of a path that the extension forms is approximately equal to a length of the extension needed for the tunnel. The kit body may include features that allow the connectors of the extension as well as implantation tools to be retained within the kit body while being easily accessed when needed during the procedure. The kit may be coupled to the patient during the trial period, as the extension may have an implanted distal connector while having a proximal connector coupled to an external stimulator and while being retained on the kit body.