Towing in cruise control isn't a no-no. As long as the transmission isn't hunting for a gear all the time it's fine.

If you anticipate some of the hills with your right foot the transmission won't make those 1000 rpm jumps. I'm pulling a 5000 pound travel trailer and at 65 mph I'm running 1800 rpm in 6th. On grades the transmission will drop down to 5th and run about 2250 rpm. Hardly dramatic. But she'll run nearly 3000 rpm if she drops to 4th and the reason I give known steep hills a running start.

What speed you running with what weight trailer?

-- Chuck