I could have added this to another thread, but here goes.
My wife and I picked up our new E21 a week or so ago, and towed it home to Smithers from Chilliwack (~1050km, 650m). The drive didn't include high mountain passes, but did have numerous moderate climbs, including the long one out of Cache Creek.
The tow vehicle is a 2014 Tacoma with the standard tow package and 4 liter V6. I put in a Scangauge specifically to watch transmission temperature. Since this was just a trip to pick up the trailer, we were relatively lightly loaded, but I do not have specific weights.
Overall, we were very pleased with the performance, and absent issues on longer trips, we will be keeping the Tacoma. A Tundra or other half ton was our backup plan, but we like the Tacoma, and hoped to keep it.
We found hill climbing and passing were acceptable to us. The V6 has lots of power if you ask for it. Only the steeper hills required dropping into 3rd gear, and less steep ones needed 4th. On all but the steepest hills, the truck was happy staying at 90kph (56mph). We stayed in 5th unless the transmission dropped out of it, in which case we dropped into 4th until the road leveled out. Staying in 5th reduced fuel consumption somewhat according to the Scangauge, but by exactly how much is difficult to say. At any rate, transmission temperature on long stretches during 5th gear were always a lot lower than when climbing, so I plan to continue using the higher gear rather than always towing in 4th.
On the longest climb, the one out of Cache Creek, the transmission temperature maxed out at about 104C (220F), which is well below the 110C (230F) stated by our local Toyota dealer to be the safe limit. This was during hot weather, probably in excess of 37C (119F) perhaps well in excess because the climb was all on south aspect blacktop. In any case, I was quite pleased with this result. I do not mind using higher revs on the engine to generate the needed power, but transmission temperature is not negotiable. That was and still is the deal breaker that could send us to a larger truck. I will be replacing the ATF with high end full synthetic Red Line stuff before our fall trip, which in theory should drop operating temperatures further.
Towing behaviour was fine, with no response whatever to big trucks passing from the opposite direction, and slight steering response but no instability from trucks overtaking us. I could generate slight sway which quickly damped if I deliberately jerked the steering, but nothing like this small amount of sway ever happened while driving normally. This was with a beefy WD hitch, but no sway control installed. I have now added dual cam sway control, and will be able to report results later. We did not have serious cross wind on the trip, so I can't report on that. At this point, I would be very surprised if the tow behaviour becomes a problem.
Our fuel consumption as calculated by the Scangauge was ~17l/100km (~14mpg US). This should be reasonably close, but may not be perfect.
I will report more results from our first long trip later this fall, but at this point, we are quite happy with the Tacoma. A larger truck would mean less need for using the transmission to generate climbing power, but I will accept that compromise in order to have the smaller more maneuverable truck when not towing. Also the better half hates the idea of a larger truck.