Depending on the aspect ratio of the video and playback viewport, you could move the subtitles into the potential black bar underneath.
If there is no black bar, you could get one of those long narrow LCDs off AliExpress, set up the driver, add it as an X display with the right positioning... and then drag the mpv window across that and the TV. Should work. Those little LCDs are just silly expensive though...
If there is no black bar, you could get one of those long narrow LCDs off AliExpress, set up the driver, add it as an X display with the right positioning... and then drag the mpv window across that and the TV. Should work. Those little LCDs are just silly expensive though...