Thanks again chewitt
issuing the command produced an error. The OS wanted an [Install] section added to the file. I added the section with a WantedBy directive and arbitrary picked kodi.target for the value.
Once it was added it I ran the 'systemctl enable /storage/.config/system.d/add-route.service' command again which worked and upon reboot the route is added.
Thanks for the help!
My file add-route.service looks like this: