In looking back at this thread I misread OPs first post. I thought he wanted to eventually tow a 7-9k lb trailer, but he was actually referring to eventually having 700 to 900 lbs in the truck. In that case I do think a half ton could work well, although I'd make sure it has all the heavy duty payload and towing packages because that setup will be tight on payload and axle ratings when loaded up.
I still think it would be worth looking at heavy duty models, though, provided you don't already have the truck. The tow tremendously better and you wouldn't have to worry about being tight on your ratings. They're no less comfortable as daily drivers and no more expensive once you add the payload and max tow packages to a half ton.