I'm thinking that cutting holes in the outside wall of your RV (if that is what you are suggesting) is just asking for leaks. Also, you'll need to use high quality "marine rated" speakers that will hold up in a damp or wet environment. Normal speakers won't last long outdoors.
I would think a better solutiuon would be to hang a pair of small "bookshelf" or automotive "surface mount" speakers off the awning. Then find a way to run your wiring so that it is not dangling and getting tripped on. Maybe even route the inside wiring to an exterior compartment with speaker jacks and then plug the speakers into that. If the weather gets bad, just bring them inside.
1995 Coachmen Santara 360MB 36' w/slide.
Ford F53/460 chassis, 1997 Jeep Grand Cherokee "toad"