I said Jk because I wasn't sure if the fumes from the 2 cycle engine would make the plant smell like oil/gas? My clothes usually do after using it especially for longer periods of time. An extension cord with a box fan might work as well.
I couldn't tell you what materials would let 60%-70% of sun light through. Anyways, it sounds like you already have your mind made up. You want to grow on your open terrace using plant covers. If someone does happen to notice them they could easily steal the plant being it is on the first...
I just googled plant covers because I wasn't familiar with them nor have I had any experience with them. They might let more light over the lattice. It's a shame you are not on the 2nd floor with a balcony. Both Lattice/plant cover seem risky IMO.
Oh ok. Yea I don't know much about auto's beside they auto flower heh. Well if you are trying to conceal them maybe use some lattice to let some light in on the left right front? I don't think I'm fully comprehending your situation. How much room are you working with?