I apologize but I ended up moving to the GNU AVR toolchain as a research exercise and realized some major reductions in the compiled size on ATtiny85. I believe when I was poking around I used the defaults and it was with a simple blink sketch but it's possible I was using the Adafruit_NeoPixel library which definitely used the millis() function among several others, so that may have contributed to the difference in sketch size.
I've now switched to a different LED library, using the GNU AVR tools, and tweaking optimization, my sketch on the ATtiny85 comes to 712 bytes for a repeating rainbow cycle driving a few hundred ws2812b addressable LEDs. So I'll probably be sticking with that for this project.
It sounds like you've got some warm leads on some optimizations you can make. Thanks for the quick attention.