How do I set a respawn angle?

So far I haven't found a way to make the spawn point command set an orientation, However you could allow a few more commands which would make the player spawn and then immediately turn to face a different direction:

New commands in a looping command block:

/execute ~ ~ ~ detect ~ ~-1 ~ minecraft:emerald_block 0 /setblock ~ ~-1 ~ minecraft:command_block 1 replace {auto:0b,Command:tp @p[r=2,] ~ ~1 ~ [ ]}
/setblock ~ ~ ~ minecraft:stone_pressure_plate 1 replace 

This way every time they die they will activate the command block and this will also mark checkpoints as taken as an added bonus, there are other methods using scoreboards and allot of commands and an armour stand but it would go on for too long here.