A friend has two 6m tubes of 4 inch stainless steel (un polished)that he had left over from a fancy farming rig he was paid to build.
He is happy to sell as bars but can also make them into an A frame. He was going to make me an A frame for my 4m Searider until I actual saw how thick 4 inch tube is. Massive over kill!
Would suit a bigger RIB if it's to be made into an A frame.