Up until now I have been planning on a Neopixel ring and a couple of rotary encoders for a user interface.  The Neopixel ring works great and I can use different colors for different uses.  I have come up with a workable system for entering small numbers and displaying on the ring but I really need an alphanumeric display - at least three or four digits.  

In normal operation the three digits would be the processed heading.  Several adjustments need to be entered: filter Q, Doppler frequency, averaging, azimuth adjustment, etc. 

The typical  location for this device is in a car with normal lighting so that's the issue.  It needs to be readable in possibly direct or almost direct sunlight.  I've ordered a few small paper white displays and a 24 LED ring.  Perhaps mounting the paper white display inside the ring.  This arrangement would be nice but is awfully expensive for what is needed.  Any suggestions?