If you are only using the Beam to play audio from your TV, you should be able to use it without WiFi. Just be sure you set up the Beam on your home’s WiFi first, install any updates for the Beam, and enable TV Autoplay before you move it to the RV.
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You might consider a travel router to connect your Beam, music library and controller to. That would stay stable as you moved around and if you wanted outside data you could connect the travel router to the park WiFi.
We RV’d for many years with a home-brew travel router and it was great to only have to tweak one setting to change to the WiFi at each new park. It was also nice to have our own local and private LAN behind the router if we were at a park or boondocking.