Usually, the four pin connectors have wires for ground, right & left turn sig, and parking lights. 5-way connectors add a wire for brakes, 6-way adds battery, and 7-way adds back up lights. Brakes are usually self-grounding, which means that current is only on that line when TV brakes are applied. Turn sigs and park lights are only on when TV lights are on. So, assuming that you have the 5 way with brakes, there will be no constant voltage, even if TV is running.
If you also have a 6 or 7 pin connector, in addition to the 5 pin connector, then you could connect the wire from your camera to the battery connection (on the 6 or 7 way), which should be a constant 12V. If not, you would have to run a wire on the TV from a constant hot lead back to the connection with the camera. Include an in-line fuse at a convenient accessible point. BUT - if you connect the camera either of these two ways, be sure not to leave it connected once the TV is shut off, or you will drain your TV battery.
2003 Ford F-350 V-10 Crew Cab 4WD Long Bed
2004 Jayco Designer Medallion 29 RLTS 5th wheel
Bill, Gayle, and Mindi (dachshund)
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