In terms of space, I think they'd have plenty of room. I think they have more room than a 3 door Suzuki Vitara, and a family friend had no problems with baby and babyseat in the back of that. When my ex and I were buying a 4x4, the fourtrak was one of the options we were looking at, we were surprised how roomy they are.
Still, you may be just as well looking for a decent Disco. Even more room than the Fourtrak, and its a Land Rover (obviously!! lol).