No longer camping with a Hi-Lo. Have a CalMark Sunbrella Fabric cover that was made in 2020 for our 2007 22T 50th Anniversary Model. Used only three years. Paid $825 (+S & H) for it, asking $350.
It's not waterproof, but it dries quickly and it "breaths". In my opinion, sunlight is more damaging than rain, and Sunbrella keeps the sun off. It will block "driving rain" however, causing it to just drip down to the ground.