and voila....it worked and nobody died!
There was quite a bit of flex in the receiver tube that comes with the hoist, coupled with the play with the square tube fitting over the round tube, but it did not seem like it was going to collapse or anything. I may add a couple stabilizing feet to the receiver tube part to prevent the lean seen here:
It's looks a lot worse in pictures! The boom extension is welded at an angle, so there's no flex there. Frankly, I should have just built the whole thing from scratch. I will probably end up re-working a couple of the pieces with thicker steel. It is nice that it breaks down for storage or it would be stupid heavy.