I've never been a pedal to metal speed freak towing. On hills depending upon the power available. If I have to shift down to keep my speed, If I need to redline it to hold 60mph, I throttle back to 70-80% of redline. This reduces the noise, I potential overheating, better mpg from a hill pulling standpoint etc. I might be down to mid maybe low 50's, oh well.
I've had rigs where the gear splits are so wide I slow 15 moh. Others same motor, more and closer split gears in trans where I drop 5-10 mph.
If the road is steep enough I have to get into 1st gear to stay moving, now said grade has my attention, especially if it's in the min 20% relm.
I deal with what I have to work with, call it a day.
Marty