I'm not sure that you will find something that you are able to just buy off the shelf to do what you want, but it shouldn't be hard to find something similar, or even have something quickly fabricated, that will allow you to mount the standard wall mount to some kind of pole, arm, bracket, or however you want to mount it. Something like a donut pole may do what you want (with a little imagination). How pretty it will look will be up to whatever components you can find to make it possible.
Wayne
Please remember to mark helpful responses and to set your question as answered if appropriate.