Bending a Long Radius in EMT Conduit?

I need to bend some 1" electrical thin wall conduit into a 6' (six feet) radius and a couple of 6" (six inch) radius bends to make some ribs to
hold up a tarp on my trailer. You can see a drawing of what I am writing about at the link below. The smaller radii look like something I could do with a regular conduit bender, but what about the longer radius? How to make such a bend? A do it to make ten identical such ribs? -- Fred
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