Colorado Diesel

I don’t know about the Colorado/Duramax, but I have experience with a similar vehicle in the Jeep Liberty CRD with which I towed a 21 foot TT with a GW at 5,000 lbs. The I-4, 2.8 liter diesel in the Jeep was rated 188 hp, 335 ft-lbs, and I got around 14 mpg with it. It had only one issue dragging the trailer up the 11,000 foot, 6-7% grade on I-70 west of Denver: a tendency to overheat. I could do 65 mph until the temperature started getting high. 5,000 lbs is all I would want to tow with that size engine. And the Jeep’s successor, a BMW with a 3.0 liter I-6, rated 265 hp and 425 ft-lbs and while it also gets 14 mpg towing, the overall towing experience is much better. So I am thinking that your 27 foot trailer will be too much for that Colorado. If you can even do it, you won’t like the experience.

I'd say I'd really never trade down to a little truck from a full size to tow a trailer that size.
Would I tow with it? Sure, but not if I had a better option.
And be use eyiure asking the question, you should stay with the safety and capability fi a full size.

FWIW, we had a 1984 Chevy heavy half ton with a 6.2L diesel which had 130hp@3600rpm and 240ft/lbs of torque and it pulled our Nomad Century 30' TT several years around the Midwest and a trip to the smokies - Cades Cove etc and over the mountain to North Carolina and the Outer Banks on the Atlantic.

We've always lived in West Michigan on the lakeshore and often went to and all around the U.P., Wisconsin etc. too. Wasn't fast by any means but always did the job OK. Also pulled our 27' Sea Ray cabin cruiser (26' 8" on a heavy dual axle trailer with 45 gal of fuel onboard - a little over 8500 lbs total) all around the state and in and out of the launching ramps with the 6.2 diesel with no problems. Slow climbing steep hills with the TT or boat but always made it up and over. Sold it with 168,000 miles and never had any problems with it. Less power than the baby Duramax has but was a heavier truck. Of course, back then, RV's had no slide outs in them but did have a much heavier frame.

Yes the Colorado/Canyon pickups are narrower than a silverado/f150 so you will need strap-on mirrors if you want to see the trailer sides. But narrower also means easier to park in a parking lot along other cars.

I've been VERY HAPPILY towing my 30ft 7K TT with my 2015 3.6l gas Canyon since 2016 (16,000+ miles). With a properly setup WDH and TowHaul my rig passes up semi's and other full sized pickups going up hill. I can easily pull my 7K TT up a 7% grade doing 75 MPH in southern WVa, northern NH, and VT mountain interstate highways.

The secret is the factory installed TowHaul which lets the computer control the engine speed AND transmission gears for maximum power output. If TowHaul is NOT turned on, the truck will be a dog when pulling a 7K TT. (Could be what Bionic Man experienced.)

IMHO, your diesel version should not have any issues pulling a 27ft TT that has a GVWR below 7,700# AND you use TowHaul.

It really depends on where you are going to pull the trailer to and what the actual weights are of the trailer (unloaded weight and max weight loaded/GVWR). Only you would be able to answer this. Any real mountains involved or basically flat to rolling terrain and shorter distances. Trailers 27 feet long weights can vary from about 4800 lbs to over 8,000 lbs loaded to travel and pull and the hitch weight will vary from under 500 lbs to over 900 lbs.

Regardless, a 27' travel trailer is a lot of length behind a lighter weight and smaller size tow vehicle. Will it pull it? yes of course it will but so much depends on where and how heavy the total rig is including all passemgers and their weights. It all adds up fast. Certainly would want to keep your max highway speed at well less than 60 mph. You surely would be pushing the envelope on safety but doesn't mean it will surely fail or crash. It's the nut behind the wheel which is the biggest factor as to if the nuts in the rig and tow vehicle remain in place or scattered about.

Remember that bumper pull TT's can or will sway a lot when buffeted by the winds created by passing trucks both in your direction of travel or passing by gpoing in the opposite direction. Also by strong side winds even 20 mph. The heavier tail will wag the dog (tow vehicle) and the the smaller/lighter the tow vehicle is the more white knuckle driving is to be expected. Often wind/buffeting action can cause a hard or violent quick side pressure on your rig and worse when the tow vehicle is smaller and lighter or has a shorter wheelbase length. Speed only makes the action worse until a loss of control and that's no fun even if you don't crash.

Braking is not the real issue as the trailer has 4 wheel brakes and should be set to pull backwards on the tow vehicle when applied. However, an emergency quick turning action the avoid an accident could easily cause a rollover and more so with a smaller lighter tow vehicle.

I believe the GDE tune brings it to like 220 HP 440 TQ at the crank. With that it would move a 6,500 TT well enough but like the others I am not sure of the stability of the narrower wheelbase. Even if you can see around a trailer that long with tow mirrors. Be great for towing a boat. The turbo diesel probably would move the TT as well or better than a naturally aspired 5.3 at altitude at least if its an older 5.3 with an older transmission. Mileage is where it would shine towing. Many average 14 or 15 mpg towing a TT even towing 65.

That truck is too narrow for that size of trailer. Need huge mirrors to see behind you. Turning is an issue with the width of the trailer with a small truck.
Been there before with an S10 towing. Just my opinion.
Curly

Not the weight police, but I would say absolutely not.

My buddy has a Colorado diesel. Loves it when it is running, but he has an ongoing problem where the gauges go crazy and then blank. Been to the dealer multiple times and they can’t figure it out, and he just missed the lemon law in our state.

He regularity tows a 15’ enclosed utility trailer (he is a contractor). He did one trip to Texas and with a steady head wind and a full trailer he couldn’t maintain 65 MPH.

He does like the MPG though.

I believe the tow capacity of the little Dmax is 7K or just over that. That would seem like a lot of trailer to pull with that midsize pickup. The I-4 is 186 hp and 380 pound/feet of torque. I would venture to guess that it will not pull like a 5.3 would.