Happy medium between comfort and good gas mileage to haul?

Have you looked at these?
Palomino solaire ultralight. It lists as 23'4" and is really light. The Dakota might be able to handle it. I don't think you'll be putting 3000 lbs gear in it. It will probably be closer to 5000-5500 lbs loaded. Which means a tongue weight of around 650-825 lbs. So if that is within specs for your Dakota you could try. I suspect you will ant a larger vehicle sooner than later though.

Here is a lighter and smaller tt by forest river. Forest river micro lite