20" 404" would be different. Not a lot of use for that bar for most people though. I'm good with 3/8" in whatever drive link is easiest to get through a 12x12.
I would do bigger but my cant stand was built with 8x8 10x10 cold start back in the day.
Your stand is built for bigger cants and other folks building stands now days. If someone else would like to do the testing.