If I understand you correctly your cutting the whole long diagonally which will include the pith. If you leave it fairly thin, 1/2" or so you could dry it successfully by putting it in a plastic bag and turning the bag inside out every day. It will slow down the drying dramatically but will keep it from cracking. It will dry faster this way than the whole long. The whole log will most likes split and probably not where you want it to. If I didn't read you correctly then Neever mind.