Bhargava,
The self-standing feature is a joke, especially in nature photography. If you need three legs, then go for a tripod where you can adjust the legs according to the undulating terrain. With proper technique, one doesn't need to depend on such self-standing features.

The manfrotto 681B monopod is fine. If you want light weight, then you can try the Gitzo monopod. The monopod also helps as a walking stick while trekking, especially climbing a hill.

Cheers,
Sabyasachi