Well, I'm officially retired now and have time to monitor that tarp. My structure is flat and easily take a broom and brush off the excess water. It won't be there 24/7, but it will be fastened with Eye-bolts when I need to attach it for longer periods of time. --BB
My husband and I figured out a pretty nifty way of dealing with those tarps. We inserted flexible PVC into flag pole holders we mounted to each side of each run, forming arches over which we can drape the tarps, and then secured the edges of the tarps with bungee cords looped through the grommet holes and wrapped around the top of each panel frame. It sort of forms a big umbrella-type look that lasts much longer than tarps simply stretched across flat, and it was really inexpensive to do.