Sounds like a job for a mountain bike. You might not think you need suspension, but a decent fork will give you much more control and comfort. You probably don't need disc brakes because the Vee brakes are so good, but there are modern discs that rival the weight of Vee type brakes. Any decent mtb with a relaxed, stable geometry and a good fork will work. Rear suspension would be a bonus, but to keep a reasonable weight will be more money. As with any bike, fit is of the utmost importance.