Tailwind hitch solution
My experience with the manufacture supplied hitch was limited. I only used it for less than a dozen rides. It finally gave way when the joint was under pressure and I leaned the bike over on the stand. The part was cheap enough @ $12 but so was the construction. It was cast aluminum and it's design was very flawed in that it allowed very limited movement. It could've been built better for durability.
In terms of durability your best solution would be to, if possible have a machine shop weld something for you. Steel will outlast cast aluminum. It may cost more but I'm sure you'll enjoy it that much more.
Good luck.