La Bella Gold Flats might work. Heaven knows, they're no good for electric bass due to low output. They may work well for acoustic bass though.
760FGS-B Deep Talkin' Bass Gold Flats - 5-String | La Bella Strings
They feel, look, and smell like 80/20 acoustic strings, only flatwound instead of roundwound.
760FGS-B Deep Talkin' Bass Gold Flats - 5-String | La Bella Strings
They feel, look, and smell like 80/20 acoustic strings, only flatwound instead of roundwound.