Stick it in tow/haul mode (practically) all the time; you have a heavy load all the time. If I'm not mistaken, tow/haul will automatically downshift when descending, but if it doesn't, do so manually to use engine braking for long descents.
Cruise control you'll figure out. It often doesn't work too well in hills and even worse on long grades where it can't come close to maintaining speed (going up) or doesn't know enough to slow down (for the downhill).
When you get a chance (after the borders are reopened), definitely take the trip along the ice fields parkway, and plan on camping along the way. It's a phenomenal road, and if you have the time there's plenty to see and enjoy to fill a few days. Reservations for campgrounds are highly recommended if you want to avoid having to dry camp in the overflow areas.