I find tow/haul not much help in climbs. I will go to direct (3) and maintain rpms as best as can be. I do use t/h from a stop on hills and sometimes on going down. Other than that find it of little use.
we tow a 2700lb hyundai and I was down to 25 going up wolf creek in colorado, just after the switchback at the maintenance yard. crested finally at 36 mpg! I do run a 5 star tuner and it seems to help, going thru denver had almost no throttle response at 7000 ft, was able to keep up between 60-65 but that was with pedal to floor. At 8000ft on the high plains had no issues maintained 65mph and had some response to throttle inputs.
Like others I do not like 4500-5000+rpm surges, but I will live with them to keep the rig going for short spells. I run a scan gauge and the most HP it has indicated even at 4500rpm was 245 pulling a hill out on rte 77 from mammoth, az. So I am not real sure where the actual peak hp torque match up.
As to unhooking, several guys I spoke with do just that when encountering high/hard pulls. I cant, wife does not want to drive the towd or in mountains! So I guess I will continue to make do. I am planning on getting a better free flow muffler and am trying to find a good free flow air intake.
Again these are my observations, thought on the matter. there are many that disagree but that is to be expected on any forum.