Your Toy Hauler would've been prewired for a Furrion Vision S camera system like # FCE48TASL-05. The rear camera would install at the back of the hauler above the rear door just as you describe, with the other 2 installing on each side of the toy hauler. The 5-inch color touchscreen display can display up to 4 camera inputs at a time, which is a nice feature to have. The cameras provide night vision and motion detection.
I've linked you to an installation video which you might find helpful. view full answer...
The best storage cover for your 2016 Jayco Octane 161 is the Adco Olefin HD part # AD97ZR which provides the best protection, easiest install, and has access panels in case you need to get into the RV. view full answer...