Installation of RF communication equipment's in vehicles can be challenging due to the physics of transmission signal and isolating materials. It is highly recommended that the installation done by professional who understand those physics.
General guidelines regarding wireless setup can be found in 1.3.1 General Wireless Setup
General
Gateway in truck and loggers in trailer
Gateway ant loggers in the trailer
Gateway in the Distribution Center and logger in the Trailer
Gateway placement
Gateway in vehicle
Gateway at Distribution Center
Truck and trailer
Only Trailer
Gateway placement