I occasionally tow my 6000# John Deere tractor to the dealer for servicing. Including the 16" tandem, the tow weight likely quite close to the max spec 7700#. The terrain is hilly, yet - if it weren't for the mirrors - I'd hardly know the load was back there. Yes, there's a little more downshifting on hills; mostly into 7th, rarely into 6th. Fuel economy suffers, but still comes in at a rather impressive 23 mpg or so. Footnote: if you have LCA, be advised that it's automatically disabled when the towing module detects an electrical (trailer) load.