That is your issue. Nothing to do with the integrity of your 3pt. IF your going to run in reverse utilizing the 3pt take it slow. I have never used a land plane and do not know how it works but I suspect you were trying to take to much at once or going to fast or a combination of both.Just the one side, it caught on a rock and twisted. I have ordered a replacement and hopefully it was a fluke.
We always plowed our driveway in reverse on the farm with a back blade. The blade was the weak point thank god. I don't know how many times we caught the corner of the blade and would stop the tractor. 65 hp 3rd gear in reverse is not slow.This.