So one of the issues that came up is LED light shining through holes drilled to allow air to circulate through the dome. While several ideas about shielding the holes and redirecting the airflow occured to me, a simpler option (of course) would be to just turn OFF the LEDs. Or you would think so.
After much web searching and several failed trials, I finally managed to get both the Pi 4b and Pi 5 LEDs to go off, and stay off.
Edit the file /boot/config.txt with you’re favourite editor (I use ViM) and add the following lines to the bottom:
# Disable the PWR LED
dtparam=pwr_led_trigger=default-on
dtparam=pwr_led_activelow=off# Disable the Activity LED
dtparam=act_led_trigger=default-o
dtparam=act_led_activelow=off# Disable Ethernet port LEDs
dtparam=eth_led0=4
dtparam=eth_led1=4
This settings seem to work on several different CPUs and Raspbian releases (at least so far).