A neutral would not be a problem as there is one available in the box. The biggest problem (which is not a problem for me, but will be for 95% of the other guys) is going to be box fill. The original design had two toggle switches in a two gang metal box with mud ring. Since "inception" we have changed the light switch to a switch/GFCI combo, which in itself is a tight fit with the mud ring. To add a timer we will have to install deep boxes. problem being, we are dealing with apartment maintenance guys and not electricians. Fortunately, all of our wiring is in FMC, so writing the "instructions" should be straight forward. I just need to find the best device for the job. We are leaning toward the spring-type timers as they are reliable, time-tested, and readily available.
Thanks for all the input
"We can do it, you can't help" said my son to the HD guy