After a bit of online and in store research, I think I found a good solution.
My local car stereo shop is going to put in two of these:
https://www.carid.com/concept/concep...3135839.html]]
One will go on my truck and the other on the trailer. They will also install a video switcher so I can toggle between the two.
As my truck is old, I need to upgrade the stereo, so the unit I'm getting will come with a 7" flip up screen and I'll be able to select "always on" for either of the cameras. This will enable the trailer back up camera to serve as an observation camera as well.
The owner of the shop has this setup on this truck and 5th wheel toy hauler and says it works great.
Hope this helps.