They're coming out with stronger and stronger gas engines. It wasn't that long ago when the 350 cid was the norm for towing with a few larger engines available. Now there are all kinds of strong towing gas engines on the market. Admittedly, "camp" trailers (mobile luxury suites) are getting bigger and heavier, too.

“In a time of deceit telling the truth is a revolutionary act.”
― George Orwell

It's not over when you lose. It's over when you quit.