Not sure if you are talking about the actual camera on the (outside) back of your camper, or the monitor you put inside your truck?
If you are talking about the monitor inside your truck, then you'll probably need to get a portable 120v normal plug in household adaptor with a transformer to plug in the 12v DC plug on the Furrion monitor. If your Furrion monitor has a USB plug, then you can use any USB power port, the same as if you plug a phone into.
Now, if you are talking about the camera outside the the camper on the back, you may need to do some re-configuring for power. Maybe your's is different, but mine came pre-wired for the Furrion (outside rear) camera. It's powered ONLY when the truck lights are on. So when the truck is unhitched and unplugged or the lights are off, the camera on the back is off.
So, if yours is set up the same way, you'll need to figure a way to power the camera when the truck lights are out, or you are unhitched.
Then, you'll want a turn off switch somewhere, otherwise the camera will be active all the time, constantly draining against your on-board battery in the trailer.
A simple solution (if yours is powered ONLY when the light of truck are on) is to use a jumper wired between pin #1 and pin #7 on your trailer umbilical cord that plugs into the truck for running lights and brakes. Running a jumper between pin #1 and pin #7 will send power from the trailer battery to the running lights on your camper and then your camera will be on. However, all the other running lights on the outside of your camper will be on also. If you don't mind annoying your neighbor campers all night long, then you could do it this way without doing ANY additional wiring.
Now, if your camper is wired for your observation camera to be turned on and off independent of your truck being hook-up, then you don't have any issues here. Half of your quest is already solved.
2019 Montana High Country 375FL
2014 Chevy Silverado Duramax, 6.6L Dually