Hey Terry,
Just an idea. Could you build a slanted cover and paint it white? I don't know if the slant would be enough to draw the fumes away from the building.
Then you might be able to run some fans in the summer if the power goes out.
I can't draw worth a crap but I'm thinking a two sided deal with a short side facing out and a long side facing in with some open gap between the sides to let the fumes out.
jim