Heavy trucks and their drivers have been going up and down steep grades for many decades, before 'tow/haul' was ever invented, or cruise control too.
Use your brains folks, the computer can't do everything and it can't foresee that sharp turn coming up, that stranded vehicle barely on the shoulder, that fast motorcyclist zipping towards you carving up the turns, that wet or icy spot in the lane, that sudden gust of side wind, that slower moving truck you're approaching fast from behind, etc, etc, etc.
Use your gears and brakes, and most of all, your eyes and brain.
