For some reason it wasn't letting me upload photos earlier. Attaching one of a particularly tricky location where there's a beam so you can't outside mount wooden shades or curtains.

https://photos.app.goo.gl/ypEJ85jMNLEj1p159

Ours look very similar but are trimmed inside and around with white painted wood. I can post pictures after we install the blinds if it would be helpful.

I’m curious why you would have to install the wood shutters outside rather than follow the inside mount installation.

I would do roller shades, maybe a double if you want to use a solar shade during the day and a full shade at night. They don't have to be mounted right against the window...

Honeycomb shades are a great option for windows like this. You can either go light filtering or room darkening and they tend to be a good fit for basement windows.

I received and installed mine and they are great! Daughter just had sleepover and no light with 3 east facing windows!