If you haven't tried them, use a peat sponge designed for clones (root riot, rapid rooter, etc) and just put the taproot in it the same as you would in soil. I use a clear solo-cup for the same soil FFHF so I can check the root development, then stick that in a regular solo cup to keep light out. You shouldn't need to water at all until you see the seed-leaves or the first true-leaves.