If your trailer does not have LED running lights, a conversion to them will help up the voltage. We have a 39'4" 5th wheel and a CC SB pickup and our Furrion camera still works 10 or 12 lots away from the trailer. I find it distracting to have it on when traveling however. Ours is powered from a inside 12V sconce light next to the rear window, so nothing else is loading the circuit when using the camera.
https://www.walmart.com/ip/Furrion-Digital-High-Speed-Wireless-Observation-System-With-Camera-Monitor-and-Mounting-Bracket/53998483?wmlspartner=wlpa&selectedSellerId=0&adid=22222222227045565836&wl0=&wl1=g&wl2=c&wl3=88838127889&wl4=pla-195640146529&wl5=9030012&wl6=&wl7=&wl8=&wl9=pla&wl10=8175035&wl11=online&wl12=53998483&wl13=&veh=sem