OP, I tow almost the exact weight you do. Loaded with a family of 4, it uses a fraction of its power to tow. I'm on a six hundred mile trip right now and am averaging 11.1 on this trip. Of course I keep it at 58mph on the highway. I'm in flat country right now, and with cruise set, I'm at 1600rpm at that speed.... Feels like it is idling. My wife commented yesterday that as a passenger, she notices no difference with trailer and without. I wouldn't go that far, but it is close!
Anyone that doubts the EB really needs to find an opportunity to try it.