[RMcNeal]

As Dutchmen said, jumping pins 1 and 7 on your 7 pin cable will power the cameras, but also the lights. I've tried this and it does work. The "hack" I found online was to use a 15 amp blade style fuse, the same style as the rig uses in the fuse panel, as the jumper.
I don't use it regularly since it keeps the running lights on all night, but it does work.