I need your help all you Martha Stewart's! Wedding Decor question...?

Fresh flowers and lots of them, on all of the tables, all around. Since it's outdoors, the fresh flowers will blend harmoniously into your surroundings. They don't have to be expensive flowers, in fact it would be better if they were more garden variety. I went to a lovely reception that had a gazebo which reminds me a little of your setting, and they just had all white flowers of every variety. It was stunning. Don't worry about hanging things from the ceiling, use the space you have with flowers, flowers everywhere.