DA1-11 and ATC watcher.
I've spent time in towers around the country...they are quite tall with huge windows as you know.
If parts of the airport are not visible to the tower, a note is made on the charts to let pilots know.
If there was ONE controller at KLEX and he was being forced to do too many things to NOT LOOK OUT THE HUGE WINDOW, then the system needs fixing.
AND one plane with all landing lights on should have been quite distinct especially if taking off on a runway WITH NO LIGHTS.
j