OP I’m presuming you’re not towing the 5ver in the mountains in the snow. That’s a different ballgame. But any smaller trailers won’t have a need for chains in the vast majority of CO Mtn winters.
Being your truck is a big doolie, you’ll use 4wd more than in the same vehicle if it was a 4 wheeler. But not an issue. It’s a push o the button. Short of just running a single rear wheel, for normal winter driving, drop your rear tires pressure to 20-25psi and add some weight. 500-1000lbs in back will help a bunch. And the further back the weight, the better. Ideally if you’re not using the bed, put the rear load divider in and pile the sandbags at the back. Although that defeats any ability to use the truck bed really.
If you’re really thinking you need easy auxiliary traction for steep grades on maintained roads and aren’t in the category of needing chains, tire socks actually work quite well on ice and greasy snow.
That said wintering at 9kft in CO, most of the winter it’s cold and grippy enough to not even need 4wd for normal drivin around. (Apologies if I’m presuming you don’t understand the nuances of different types of winter driving, although you did ask what tires to get so trying to provide some additional guidance as tires are only part of the equation.)
