Back pack cinch top

[dadam38]

I am in the process of making a back pack, and I am going to make the top a cinch drawstring and a flap, like the picture below. I wanted to add a little flair to it by making the cinch drawstring a bolo tie. Has anyone done this before and did it work? Does anyone think this wont work? What i am worried about is that the bolo tie wont have enough tension to keep it closed. 

 

Thanks for the responses