I don't have a problem with the flexing. I just use a support block for the fix. Since this is a tapered wing I wanted the rods as wide spaced as possible so ¼” rods worked best. For a straight wing you can get by with thicker rods. I did see, at Walmart, some 5/16” x 48” Fiberglass rods. Thought about it but passed for the 1/4" steel rod. Flexing for me is not a big issue. You can use one or two support blocks and problem gone. Take a few measurements to check for straight. Once you start sheeting, flexing will no longer be a problem. .
Today I flipped the ribs over and sanded the bottom side. This side went a lot faster than the top. You just develop a technique for the How-To. I'll match these ribs to the other side then get ready to build the wing.