Buy a dirt bike! LOL
Try this to start. Lay your bike carefully on the ground and then, with all your gear on, pick it up. Repeat five to ten times. Tired Huh? The joy of off-roading, and I raced MX for a few years, is the lightness and low end of an honest off road bike. You have reached the reasonable off road capabilities with the smooth dirt and gravel roads that you have experimented with already.
Try this to start. Lay your bike carefully on the ground and then, with all your gear on, pick it up. Repeat five to ten times. Tired Huh? The joy of off-roading, and I raced MX for a few years, is the lightness and low end of an honest off road bike. You have reached the reasonable off road capabilities with the smooth dirt and gravel roads that you have experimented with already.