I have read that coach has said that any handposition is ok for the planche work, and the position I suppose he has been refering to is from straight forward, outwards and all the way back and on the fingertips and parallettes. I didn't find a comfortable position until i turned the hands inwards about 45 degrees and it works really well for me, have been doing like this for half a year. I don't know how it will work when I get to harder variations though, I only to tuck variation myself.
This idea has to be approved by the people who know what they talk about before you go ahead and possibly hurt yourself.