Randall, i had the exact same problem as the OP on one of my bikes years ago and couldn`t get my head around what was wrong so i machined a mushroom a few mm longer to take up the slack!You could machine a new, thicker mushroom.
I eventually found out what was wrong - i had omitted the large thrust washer that sits on the gearbox input shaft behind the clutch basket so the whole thing was positioned that much further back.
If the OP wants to go down the
improvisedroute to cure his issues i`d suggest placing a suitably-sized washer under the release bearing. Once positioned there it won`t be going anywhere and will have the effect of reducing the travel required for the mushroom to reach the release bearing.