Should I use cruise control while towing a travel trailer

When ever conditions allow, I always have my cruise control on. Also, have tow/haul engaged. And depending on how great in number the hills are, I'll even lock out 6th gear.

In hilly areas i'm better than it is. In the flat areas it is better than me.

I always use my cruise control with TowHaul enabled. This lets the computer decide the best gear/accelerator combination to maintain speed and fuel economy. I just steer and enjoy the passing scenery.

I have always used mine, but I am very conscious of kicking it down a gear when going up even modest hills.

I do when it is flat. I have a Ford powerstroke diesel - it has plenty of power going up pretty significant grades. However, if I don't manually lay off of the accelerator going up hills, it will max out the turbo psi, and I think I can see the gas gauge physically moving. I have found in hilly areas with the cruise on 60-65, I will get as low as 8 mpg. Through the same stretches laying off the pedal but not to the point of slowing way down (maybe drop to 55 on big grades) I can get closer to 12 mpg.

My new Arctic Fox's manual said not to (they're wussies). :B
Most of the time I don't because I just like to have the control but on long fairly flat stretches I give my foor a break.

I have a 3500 Chevy Silverado Diesel Duly. It has Cruise Control, Tow Mode, and Exhaust break. When all three are turned on, the truck (especially towing the trailer), literally drives itself, even in the mountains of Kentucky, North and South Carolina, Virginia, and even the Dakotas. The hillier it is, the sweeter it is.

Never have to touch the brake peddle or the acceleration peddle. Cruise keeps the speed steady, exhaust brake keeps the rig from acceleration on down hill slopes, and tow mode controls the shifting going up hill to maintain that steady speed when on Cruise control. I can not manually perform such actions with the same smoothness that this truck does by itself. It's an awesome truck! I tow at 60 mph on Interstates. And never touch the acceleration peddle unless forced to slow down for whatever reason.

I use it driving both trucks ( one is an automatic trans, the other is manual trans ) while pulling.
The exception is rainy wet roads. I never use cruise in the rain, towing or not.

Best thing. Check your owner's manual

If it seems to work well then by all means use it if you prefer. I certainly use mine almost always. I far prefer the steady speed to keep me under the limit but also not to lose time. If the transmission is hunting or downshifting too much or the situation needs more personal attention then just switch it off.