I only have one camera, on the camper bumper. Wire length limited me to mounting it there - it's the OEM camera for the GM NAV system.
For those that may happen across this thread in the future and are considering a trailer, I'd highly recommend getting one with torsion suspension axles.
My 6x12 had them.
My 8.5x20 has them.
I've been using my brother's 7x16 leaf spring trailer after selling my 6x12, and it bounces all the time. Every little imperfection in the road is transmitted to the truck. I never experienced that with the 6x12.
Torsion axles make for a smoother ride, due to each wheel being able to move independent of the other - think Independent Suspension. A smoother ride means your cargo doesn't take the abuse like on a leaf spring trailer.