Haloview hands down. I love having the camera on 100% of the time, like having a rearview camera, even though you have a 5th wheel (well in my case anyway) hooked up. Very clear, and with a SAN disk, it will act like a dash cam, recording everything while it is on. They also have one with integrated TPMS sensors for your trailer, to reduce the number of screens if your truck does not support the trailer ones (or does not support bigger trailer tires with higher pressures).
Good luck and have fun!
//KMac