If you're looking at a late model but not brand new small pickup with a "crew" cab --one with four doors and a back seat, I agree that the most logical choice would be a Colorado/Canyon.
I don't think you'd want to use a full-sized 1/2-ton pickup as I'm pretty sure you'd want to keep your weight down.
If you're looking for an older truck, the Nissan Frontier crew cab is towable without modification with a manual transmission ...and I believe still are. The third generation Ford Rangers I believe were towable with a manual tranny but only had small extended cab available with a rather useless rear seat.
If looking for a brand new pickup --it doesn't sound as if you are-- the Colorado/Canyon, 4th gen' Ford Ranger, and the Jeep Gladiator are all towable with their auto transmissions.
But as other have said, you can look through the Motorhome Magazine dinghy towing guides for a list of vehicles that their manufacturers officially sanction for flat towing as I was just summarizing from what I can remember.
I've linked the page that will give you the lists from 1990 to 2019. The 2020 guide will be out in March or April(?) as a supplement to their April 2020 issue.
Motorhome Magazine Dinghy Towing Guides 1990-2019