The datasheet explicitly mentions using Rext of 1k or 2k.
Fig 9 "Maximum ILED versus Rext" shows values of 1k through 10k.
Equations 4 and 5 can be used to calculate Rext.
What is the supported range for Rext over which the device will be well behaved?
More specifically I'm interested in a peak value of 2 mA which works out to a 28.7k resistor for Rext ... any issues
with that configuration?