Hanging something for sale in a public restroom might not be the best idea. It degrades your work and it's asking for trouble, framed or not...theft, slashing, disfiguring, absorbing odors, splashed fluids, any number of things.
It doesn't matter how small and friendly the restaurant is, the owners cannot guarantee 100% "niceness" in their customers.
Think about it, would you buy a quilt that had been hanging in a public bathroom for who knows how long? When was the last time you went shopping in a restaurant bathroom??
Sorry to be so blunt, but I think it would be a real mistake. Besides the physical danger, it gives the impression that you do not think very highly of your own work.