I towed a 2013 Lance 1885, on a scale it weighed 5100 lbs loaded. My 4Runner was a 2011 trail model with a V6. It did a fair job, but heavy head winds were a problem. I moved to a Tundra with the 5.7 V8 and the difference is dramatic. Our mountain passes are now much easier.
My view of performance is influenced by the fact that I carried a big truck camper towing a jeep with a 2008 F450. The rig weighed 19,400 lbs and would pull the passes with ease. there is nothing like diesel power. Old age stopped the TC business because a got too crippled to use the cab over bed. The Lance trailer has a walk-around bed.
Ron