The real consensus is 95% of the people here think you need twice as much tow rig than you actually do!
But to your question, half ton, any flavor, will get the job done as comfortably and powerfully as you’d imagine. Pilot/midsize will get the job done and it will be safe, but like Ida said, not ideal.
Short term , whatever gets you out in the mountains. Thinking long term think about the benfefits of a full-size vehicle. I don’t think the mileage penalty is that great when not towing unless you run a lot of commuter miles.
Biggest thing imo is how do you like to drive? I’m intimately familiar with most roads in the CO Rockies and when you lose 1/3 of your power and have to use your brakes 50% harder, having a little more than you actually need under the hood is nice.
If your handle was “Nebraska corn” not CO mountains, I’d say you could tow it with a Corolla! Lol