I don't think that you'd be happy with the Allez; it is more of a fast road bike than a tourer. It can't take tires wider than about 28mm, and if you want to ride on unpaved trails, you'll want to go wider than that. I would especially advise against a bike that doesn't fit you properly.

If you're comfortable using flat bars, I would go with a light hybrid. They are easy to find used, and typically have plenty of attachment points, take wide tires, and are geared low for carrying loads over hills. If you want a decent drop bar touring bike and don't want to spend a lot of money, the Fuji Touring would be a good choice. If there's an REI near you, the Novara bikes are worth a look as well. Given your load requirements, there's not an awful lot of science here. Just find a bike that you like to ride and go with it.