Joe I don't know if this would work, but in the storage area of my RV I saw a guy with about an 8.5' or so 2x4 that was laying across the roof, right near the corners. I didn't get why until I asked him, same reason as you pointed out - the cover would bend and break off his rain gutter spouts. What I saw was the 2x4 had rounded corners and was covered with something, maybe duct tape.
Now we live in the desert but he'd moved here from Oregon so it made sense. But I did warn him that due to our high winds it might not work out. He must have moved or sold it since I haven't seen him in a few years, but well there is any idea that I've seen.