Thanks all!
I decided to go with Woolite. I took it outside after cleaning off the driveway since the blind is too large to fit into anything.
I mixed some water with Woolite & using a soft brush cleaned the blind & let it soak for a good while. It decreased the stain by at least 50%. After using the hose and washing it out, I repeated again & this time it was soaking for quite a few hours & I was quite generous with my Woolite on the bad stains.
By the end of the day, the stain was minimized to a small area of about 2" and only on one of the pleats.
It whitened quite a bit, but maybe also because it was in the sun for maybe an hour too.
I only did this on the night half of the blind. I haven't tried it on the thin fabric part of the blind.
Again, thanks!