Hopefully this will provide some inspiration for any sound bar mounting needs. We had a unique situation but it doesn't look like TCL makes brackets for what we wanted to do. With some trial and error and some spare parts, we were able to get the job done, and luckily it turned out clean and sturdy.
This same idea likely could be applied to any TV and sound bar set up. These are the device models we used:
TV: TCL Roku Model No. 43S435
Sound bar: TCL Alto 6+
What's on my tool belt?: https://makingmends.com/toolbox-essen...