Esjay-
I know what you're going thru. I am a hard core Honda guy, and will be forever, but Honda doesn't offer anything for towing over 5k.
The Ridgeline is a GREAT SUV/Truck for a 3k trailer. I've towed a lot more with a Honda Pilot, but in state only. As we opted to begin traveling long distance, I wanted something larger so I we don't "feel" the (large for a Pilot) trailer behind us so much and a day long drive isn't as tiring. It never felt unsafe, we just always knew it was back there! So, we bought a 2010 Sequoia Limited this year, practically the same as the Tundra, but with coil rear suspension.
Never mind the chassis and truck talk between the two, that's a conversation for fools. But what they have right, is that the two trucks you are considering aren't really comparable. They are designed for very different intents.
With your current trailer, I'd pick the Ridgeline hands down. For all the time you are not towing, you will be VERY thankful for the smaller Honda. And forget the EPA MPG ratings, you'll get better MPG in the Ridgeline in every situation! Towing MPG is almost the same, but the Ridgeline will almost always be the better. The difference here is the Ridgeline motor will need to REV to get needed power. If you don't like to REV a gas motor when towing...do not buy this truck!!!
The Tundra however, is future proof for you, and you will hardly know your current 3,000lbs trailer is behind you. If you tow often enough, you can work with the trucks size and truck feel, you can deal with low everyday MPG (14-18 winter/summer), higher common maintenance costs, and you can afford the price...buy the Tundra.
Don't be afraid of the used market for the Tundra. Just take more time to shop it and wait for the right deal. The 2nd generation and newest generation (mechanically almost the same) are absolutely rock solid trucks. (Ridgelines are too!) Used dealers just need dialog with you to believe you're serious before they offer better pricing!