I can contribute somewhat. To answer your question in a short way, It depends. To answer it more thoroughly, read on.
I wouldn't pull that thing across country, but the Colorado will definitely do the job for 140 miles.
Is your new truck a dedicated tow rig or is it a commuter truck/daily driver the rest of the time? Do you like to go fast? Both make a pretty big impact on what truck you'll be happy with. Colorados are way easier to park than Tundras. Hell, my wife won't even drive the Tundra.
Alright, let me explain where I'm coming from. I'm long winded so if you get bored easily, bail now.
I have a 18' car hauler that I pull my crawler on and it weighs 5400-5600 depending on gear sometimes more or less. It's not exactly aero friendly but it's no box. I Tow it ~400 miles every 4-6 weeks.
First tow rig was a first gen tundra with the 4.7, a very similar motor to what you have, albeit made less power back then. It towed great. Then, I had a 5.3 suburban and it towed terribly compared to the tundra even tho it was larger than the first gen tundra by quite a bit. They have the same amount of power, but the Toyota transmission was better than the Suburban. Tundra tow rating was 7100, Suburban was 6800... oops back to the subject.
The diesel Colorado tows better than both of those trucks did.... unless you like to tow 80mph and then either gas truck will out perform it (but only at that speed) The Colorado will outperform most small gas v8s at everything except speed. If you like to go fast, you'll miss your v8.
The Colorado doesn't have the horsepower, I presume, to keep a load moving through the air that quickly, which brings me back to the point I was trying to make.
All that being said, i think the wind resistance pulling that trailer is going to be tough on the Colorado, if you're wanting to drive fast. If you like to drive 65 when you tow, you'll be golden.
I took a 1100+ mile trip last month (not towing) and experimented with speed and mpg and you literally get 1/2 the mpg at 80mph than you do at 65. Yes, you read that right... 30mpg at 65 down to 15mpg at 80. Dang aerodynamics, you can't trick them.
Tim