Just take your main down, pop the kite and snuff it just before you hit the beach...... (I am joking)
All jokes aside (nice pic BTW!) never ever use the spin without a main or with a reefed main. The main is what supports the top of your mast. Without it the mast will invert under the spi pressure and you risk breaking it. So keep the mainsheet tight and keep you main up when using your spinnaker.
