250-500cc Best Way To Drain Coolant From Case?

Had a gasket fail during a new top-end job on my wr250, and ended up with coolant inside the case.
What's the best way to draining the coolant?

Please don't say I need to pull the jug...

Game plan for tomorrow.

Pull the spark plug.
Flip the bike over, and in 5th gear...rotate the rear wheel to pump out the coolant.
Flip back and add av gas through intake to try and dilute any remaining coolant in the case.
Crank a few times, to mix av gas throughout the case.
Flip the bike over again to drain for the last time (sounds messy).
Flip back to normal and install spark plug.

flipping the bike over is the most reliable way

Flushed the case twice through the intake manifold with oil/gas mix.
Flipped the bike and drained it through the spark-plug hole each time.

Looks like coolant is holding this time