I agree pretty much with you Dan and tend to be on the conservative side as well. The western states do have much more dramatic terrain in terms of grades and elevations, while some mid-west states like Kansas have unusually high winds. It comes down to "picking your battles" so to speak.
I know that no one is more conservative than American Honda when it comes to rating their vehicles and if they say the Odyssey is rated for 3,500 lbs than you can bet the chassis, drivetrain and brakes are in agreement (same engine and chassis almost as the Ridgeline and Pilot).
I wouldn't hesitate to pull 2,500 lbs with it anywhere and I'd pull more than that knowing the conditions ahead of time. This video shows a friend who tows this boat up and down the east coast. It's pretty much at the 3,500 lb limit and as you can see the Odyssey is riding perfectly level. He's never had any issues.
I do agree with you however in general terms, I just feel that the Odyssey is a slight exception and is a valid contender for the T160 if it isn't loaded down very much. I guess, as a retired Honda engineer, I just feel comfortable about the Odyssey as a sound vehicle for towing. Before Honda had the Pilot and Ridgeline, all the Honda Marine reps used Odysseys to pull all kinds of boats around the country with very few problems. Using the 20% safety margin, I think 2,800 lbs is a practical limit.
The other important rating other than the towing capacity is the payload capacity since this is the total load that the vehicle can carry, towing or otherwise. This has to account for the weight of all the passengers and their gear, fuel and water etc. When towing, it also has to account for the several hundred lbs of additional tongue weight. The Odyssey has a payload capacity of 2,258 lbs which should also handle the trailer demands equally as well.