Any clear covering will be a problem: grit/dust, falling leaves, bird droppings, pine needles, etc. I previously lived in a house near Seattle with large skylights and they had to be continually cleaned or they looked hazy, even during the rainy months. I recommend that you definitely have a slope to the roof, and that you use some kind of translucent material (perhaps twinwall?) to make the accumulated grime less obvious.

Thanks for the info. When I figure out what to do and finish it I'll post a phot or 2.

I recovered my patio in San Diego with clear corrugated plastic stuff, sold in 10 and 12 foot sheets at Lowe's/Home Depot. In 4 years or more, it never turned hazy, it did get dirty occasionally, but easily cleaned off with a hose running over it. If you can slope it like mentioned before, that will help clean it easier and stuff will run off with the rain.

My patio was the home for night blooming jasmine, that actually wove itself around the frame of the covering, so the plastic sheets were not affected. (If you can control it that way) I would just suggest a vine with thin stems/runners, something large like a wisteria or the like, could push your clear plastic covering out of place.