OMG I'm so dumb. I just figured out how to do what I wanted to start with.
the whole thing is builtin to FreeNAS. I'm such a dumb poop.
The whole time I was thinking that the Rsync could only be using with another FreeNAS server not itself.
So I didn't create a task to do that.
Once I tried it to use itself. It looks like its working.
So now I have my dataset backing up to the USB drive. and if for some reason I lose my array I would think I could import this drive and do some sort of restore.