With everything I've looked at, it looks like white is white. Maybe you can go down to a pale blue, but that's about it. I think if I get two 5m strips then I can use one on light blue and one on white and get what I want.
I think that would work out well. With the 2 strips you can experiment with many color combinations. You can even kinda reenact lightning stormsI think if I get two 5m strips then I can use one on light blue and one on white and get what I want.
The tank is going in front of a 9' wide window. I want the sunlight to come through. So no background is planned.
Also good chance of having green waterDepending on how much sunlight you get you could save yourself a little or a lot of scraping.

The overflows will look ugly from the back side, something to consider if it's the front of your house lol. I would suggest starting with a strong plant like pothos in the sump or hanging out of the tank to keep algae at bay. Depending on how much sunlight you get you could save yourself a little or a lot of scraping.