Split an onion, Too small for toothpick water starting?

My little girl and I decided to try our hand at growing some stuff this year and this guy started sprouting, so we impaled it on toothpicks and then let it grow some. Tonight we split it and the sections were smaller than I had anticipated. I am leaving for my 14 day hitch tomorrow and I don't want to plant it in soil quite yet because I won't be here to be the proactive one to protect it from weather and such. Are these too small to impale with toothpicks and grow in water? If I can, is there anything that I need to be mindful of when I do? Any other tips and tricks would be appreciated.