/tp rotation not working for boat

I can't change my boat's rotation using commands.

• /tp @p <location>
• /tp @p <location> <rotation>
• /tp @e[type=chest_boat,sort=nearest,limit=1] <location>

all work as intended.

• /tp @e[type=chest_boat,sort=nearest,limit=1] <location> <rotation>

functions exactly the same as

• /tp @e[type=chest_boat,sort=nearest,limit=1] <location>,

completely ignoring the <rotation> argument. I teleport with the boat if I'm riding it; the boat teleports without me if I'm not riding it; either way it ignores <rotation>.

If I teleport myself when I'm riding the boat, I teleport without the boat.

How do I set the rotation of the boat?

The reason I want to set the rotation of the boat is because when using WASD to turn the boat, I can never get the horizontal rotation exactly as I want it. It's always at least 0.1 off, causing me to drift in either the x or z dimension over long distances.