William Duffield
If you ripped it in two and flattened both pieces, you would still need to take a minimum of 1/4" off of each, which would put you too close to 3/4", probably under 3/4". If you ripped it in three pieces, you would probably achieve your minimum desired thickness. If it is flat sawn, the glued joints would probably show, but if rift or quarter sawn, they would be practically invisible, or at least unnoticeable to anyone but you.