I just started reading this thread but wondered if anyone has considered a pipe footing as an insert and letting the round peice set the angle with concrete nails
A would be a steel knob that would fit as an end cap like we have on tent poles
B would be at a different angle than C to provide a short offset to allow for short poles.
Base bar would be longer as now it is round and spread the weight say 1foot or slightly more.
Drill holes to allow the concrete nails a little wiggle room and the pin on the knob would go all the way thru? Maybe not, might want to keep the strength.