I have an electrician's fish tape that I bought for another project. It works well for that kind of stuff. But I think I was able to fish the wire through all by itself from the top. The hard part was getting the wire between the two panels at the rear to the light. I must have spent an hour or more attempting to fish it through with the fish tape and a coat hanger. I finally just tucked it over the top of the inner cab panel.
