Why not carry the gun in a Zip-Loc bag? You won't have to clean it unless you have to shoot through the bag.
I do, I keep a j frame in a otter box in my bag and a smaller one on me. Maybe I should look more into the Bersa 9mmcompact, it's a little bit bigger but could be my beater for on the sand. I have heard tons of great things from Bersa.