I tow an Rpod 180 camper with my 2002 LX470, Weight Distribution Hitch, Trailer Brakes, single axle, no special mirrors.
Dry weight, my Rpod 180 weights 2,841 lbs but loaded will all our stuff its probably just over 3,000 lbs.
I really wanted another camper (Coachmen 192RBS) weighing dry 4,100 lbs but doing a calculation it was just under the GVWR
and I got concerned. In any case, when I take my Rpod 180 to the mountains of North Carolina, I've had to drop to 2cd gear for the climbs.
Here is the spreadsheet I got off a camping forum some time ago - its pretty good: