I've got one, and does me fine!
It'll be a bit of a squeeze with you, the Mrs and a dog, so you might want to take a tent or craft some sort of awning for the side door too.
Basically, I've put a raised bed in the back, so I can slot boards underneath, diagonally from corner to corner. I've also got a little twin hob gas cooker on a sliding tray that comes out from the side door. Bed is only 4ft wide, but it's a full 6ft long. You just need to build it in such a way that you can fold it. I'm 6ft and can sleep in the back in a straight line, but I have to put the seats in the front forward first (no hassle to do this though).
It's cosy, and a little cramped but it's also about 1/2 the cost to run of a T5! I get about 500 miles from a £70 tank of diesel (with a roof rack), and it's £50 a tyre. In comparison, my old T5, I got 500 miles from a £100 tank of diesel, and paid £100 a tyre!
I took her down to France for 10 days last September, and stayed in it all the time, no worries. Just be aware when you fit a bed etc, that there's only barely enough room to sit on the bed, without banging your head on the roof!