Well, I figured it out! Thank goodness.
So, I mistakenly thought I could locate a "reverse wire" on the steering column harness. Nope. Not quite. However, after some research and fiddling I have now become aware of the Neutral Safety switch. It is located on the backside of the steering column and serves our motorhome two functions.
It keeps the starter from engaging if you are in gear and try to start AND is the switch for the reverse lights. It does this by having a small notch of plastic that inserts into the steering column and gets rotated as you shift gears.
My switch was bad. I could start in Drive, the starter always "slipped" and my reverse lights didnt work. I
I started to try and clean it up but a new switch is only $20 from Auto Zone. They all work fine now.
All I had to do to then was tap my monitor for my back up camera into the correct lead off the Neutral safety switch and presto- it comes on automatically when I shift into reverse!