And it occurs to me that the better mod here would have been just to grind a horizontal slot in the front of the tube (or maybe the outside edge) right above where the ball would end, and rig it up for a stout bolt or pin to pass through there similarly to how the steering shaft is fixed to the coupler.
Would've been tricky but no moreso than what I did and probably faster AND would lock the thing in against any deceleration stress.
Dang.