I would strongly suggest not to go to Nepal during OPT. If you had H1B, your case would be different. If you have just an OPT then they might reject your visa right away.  Just think the scenario, why are they going to give you visa as you have no intention to study and returning back and I doubt they will give you visa to work in OPT. As you came here to study and you did graduate already. They might not let you come again unless you are going to school again. Just Be Careful.
One of my friend had same situation and he went back to Nepal. He got rejected twice but again he applied for PhD and got I-20. So, they gave him visa again.

This is Just my personal view as of my experience.