I can understand you want to sit higher.
As far a space goes I really think the Tucson (couldn't find any numbers for trunk size) is in the middle when it comes to space. It might be slighly bigger than an Impreza/Mazda3 but smaller than a Forester/Jetta and the even larger Legacy/Outback/Mazda6. The Forester sights higher than most cars, you might want to look at it, it was on our short list.
The Mazda3 can be a bit small for trunk space but the Mazda6 is huge. With the seats folded down you have 6 feet of space back there which is the same as a Legacy/Outback, the Forester is about 5 feet, same with Jetta but I think the Impreza is about 6 inches shorter than the Forester.
Another choice if you go with a car is by buying a roof box. I have a 15cf roof box and its perfect for loading up camping gear. At a cost of under 500 bucks is an easy purchase. Most wagons come with roof racks.
How big is your dog? Unless its a Great Dane I think most cars would offer plenty of space. The Forester has more head room than the Impreza and Legacy's.
If only travelling with one other person (two people total) you can stuff quite a bit in a small car. We use to have Protege5 and with the seats down I was able to stuff inside the car two mtn bikes, all of our camping gear (including chairs), clothes, back packs and food for two weeks.
Glad to here you like the forum. Stick around its a great place to hang out and use up your free time.