Unistrut Roof Rack/Deck Flex

Hey everyone! I cut up some unistrut for a roof rack over the weekend, and now i’m tempted to make a little wooden deck seating area for each side of my rear fan. I’m a little bummed that there’s quite a bit of flex while testing the weight with some scrap wood as I pushed down with my hand, but wondering if anyone has done something similar while keeping the overall height clearance down? I guess I could always go back and get the next gauge up for unistrut 🤷🏻‍♂️