I towed a 21' Starcraft Hybrid with my 4Runner but it had the V8 in it. Pulled very nicely and we never had an issue. It was the best vehicle I have ever owned but traded it off for a Tundra because we knew we were going to get a bigger trailer. I also did not like carrying the generator inside with us. Taking wood for fires was also an issue.
They stopped putting the V8 in the 4Runners saying that the new V6 was more powerful and efficient. Not sure how one of those would work.