Can the split screen in Mario Kart 8 be removed?
From some light research around Google, the consensus seems to be that it is a highly sought-after feature, yet it was not implemented for Mario Kart 8, for whatever reason. Unfortunately, there doesn't seem to be a way to split the screen between gamepad and TV. Off-TV play is available for Singleplayer, but when a second, third, or fourth player joins, it is not possible.
Sources: Here and here.