I made up a couple of portable Wireless Beolab 2000s usinl Beolink Wireless 1’s. You just need a power socket.
Scroll down in the article for a link to the pics. They work really well with my system but are bought inside when done with and as they have the built in IR eye they are an easy “all in one” solution.
You could look at a couple of Beolink Passives (one fitted inside near each balcony) feeding out to specialised outdoor speakers with an IR eye in the weatherproof mount. They will be controllable via the eye and work the same as a BL2000.