It depends if you want to have independent video capability in the headrests or if you just want it to show the same video that is displaying on the front screen. If you add a front camera than you'll have 1 video input remaining on the Lockpick. So, if you have monitors in each headrest you would need a 2-to-1 splitter to get the video to show on both. If you want independent capabilities than you'll be looking at having to split both video and audio which will require external amplifiers or wireless headsets to accomplish.
EDIT- Forget what I just wrote about using the Lockpick! If you use the second video input on the Lockpick you won't have video on the front screen. So, if you want the same video on all monitors you will just need a splitter. If you have monitors in each headrest than you need a 3-to-1 splitter; you'll need an amplified splitter likely too running 3 monitors off a single input. For independent video the above still stands
It stopped raining for a bit, so here are some pics of the camera and how I ran the wire into the cab.
I painted the base gloss black and you can see my KC Hilites light bar with no lights
You can get a glimpse of my clean front grill in this one
Backside of the emblem and can see the area I grinded away to allow room for the camera
Clips behind the upper grill bar to hide the wire
A zip-tie on one of the clips and then on its way behind the fire mat
Into the cab it goes
I'll get some video of the camera in action along with using the front and rear while driving tomorrow on my way to work. My Micca is set to arrive tomorrow as well