As a matter of fact, there are strollers that are suitable for many聴not all聴trails. They’re not at all unlike the ones you see at the shopping mall, but typically are heavier-duty and more stable. An example: Kelty’s Joyrider ($320). It has a sturdy aluminum frame, a full hood for protection from sun or rain, and tall, easy-rolling wheels. A bicycle-style caliper brake and full harness for the occupant enhance safety. There’s even room for two water bottles, although not much else.
A company called Baby Jogger makes a similar stroller called the Baby Jogger 3 ($340). Its wheels are a little taller than the Joyrider’s, offering better maneuverability on rough terrain. Shock absorbers, lots of storage pockets, and slightly higher weight capacity than the Joyrider make it a good choice as well.
Both of these joggers are of tricycle design, so will be narrow enough for decent trails. But I don’t think you’d enjoy maneuvering them over a trail with even a few rocks and roots, let alone steep, rough stretches or rocky streambeds. Then there’s the weight: 25 to 30 pounds for the contraption, plus baby, plus pack. That could easily result in a load of 80 pounds or more. Oof. Still, you could make it work, and you’ll get a helluva good workout!