With a 6-1/2' bed you should be able to leave your tailgate on and just open it when coupling up to the trailer. That being said you can measure from the center of the king pin to the back of the pin box and then take that measurement to your bed and place the end of the tape measure above the axle and lay it towards the tailgate to see how close it comes to it to confirm.
Typically pin boxes curve upwards toward the trailer as you go back so you'll typically clear the top of the tailgate... view full answer...
The rear camera of the Furrion Vision S Wireless RV Backup Camera System # FOS07TASF does have up and down adjustability in the shark fin mount. In the attached video below you can see the adjustability at the 4:08 minute mark. view full answer...