Good job! Soon you'll be out of sewage and into metal work. Food for thought where you punch the hole through the tube and have that Bolt probably a good idea to get a grade 8 Automotive Bolt. regular soft steel bolts you find at the hardware store you'd be amazed and how quickly that hole in that tube will wear right through it. Another option is to drill a bigger hole and weld in a piece of round tube so puts the weight evenly on the bolt and not in a cutting shearing action. You may have already done that but just a thought