If you have an aluminum travel trailer, then I would not expect that you would be able to reliably monitor devices inside the travel trailer from the cab of your tow vehicle. Since both are enclosed in a sheet of metal, they both act as Faraday shields, and wireless signals have a hard time getting from the inside of aluminum trailer to the inside of the truck cabin. If you were standing inside your travel trailer, I would expect that you would be able to use Bluetooth to configure a device from your cellphone though. I purchased a Victron Orion, and am planning to configure it while standing inside my aluminum trailer using my iPhone. Once configured, I do not expect to get good reception inside my Chevy pickup.
A week or so after making my initial post, I did a test. I used a high-tech approach to testing bluetooth reception... it included my iPhone and my wife's fit-bit wristwatch. I used the fit-bit as a bluetooth source. I downloaded a free app called "Bluetooth BLE Device Finder" on my iPhone. It's supposed to help you find lost BT devices. The hard part was finding out which device was my wife's fit-bit... I had to put it in an empty aluminum cat-food can (with another can on top) to see which signal went away.
I laid in on the counter in my trailer, put my cellphone next to it, and looked at the "signal strength" associated with the fit-bit. It was around 72. I then put the fit-bit on the aluminum floor of the TT, where I planned to mount the DC2DC. The aluminum floor may have interfered with the BT signal, because I got a signal strength around 53. I then went outside the TT (closing the door and leaving the fit-bit on the floor of the TT) and stood right next to where I thought the fit-bit might be... the strength was around 35. I walked around to the other side of the TT (driver's side of the TV) and the signal strength was 19. I got inside the truck and the signal strength was between 0 and 5. (The second time I tried the test, the fit-bit strength was 0, and it dropped off the list of observed devices). I'm inclined to think that both distance and metal are attenuating the signal. When I stepped inside the house (which has a brick front), the signal dropped significantly, so I think that the BT signal might have problems getting through other materials as well.