I use a Swift Hitch portable
camera. I like the ability to put my "remote eyes" wherever I need them.
I have a Ram 3500 with an 8 ft box and my trailer is a little over 35'. I do not have any trouble with reception.
The reason I chose the portable camera (magnetic mount or suction cup mount) is for the three usage models;
1-use to hitch boat or trailer (mounted to the tailgate)
2-use to back boat into storage stall (I put it on one of metal poles and watch side to side alignment. Once lined up then I reposition it to the rear of the stall to know when to stop.
3-ditto for the trailer. When I am backing the trailer in the stall solo, I am totally blind since I am turning while backing.
I have used the camera for nearly 4 years and have been very pleased with hits performance and quality.
By way of contrast, I have a relatively inexpensive mounted camera
on my Honda pilot for hitching a smaller trailer. Some times there is interference for no apparent reason. The Swift Hitch is very good even when it is located beyond my boat or TT rig