Thanks to all the contributors to this thread for a lot of great info. What I learned is that for my 20' dual axle box trailer, I may be able to get away with just moving the receiver on the truck. I attached a length of 1" wide steel bar to a bracket behind the license plate and moved the receiver to where you see it in the below photo. I was able to do this using the existing service loop and connector, so no need to add an extra length of cable. Test so far have shown that this method works great. We'll see how well it works in the rain. It's somewhat protected by the spare tire, so I don't anticipate any failures. Then again, we don't get much rain here in SoCal.
Thanks