I may install a uv light and I have read that it has features for it as well.
That is only a reminder for bulb replacement. Just like the air filter change interval and humidifier pad replacement interval.
As far as humidification for your rooftop unit goes...
What state are you in that's dry enough to where you and your friends are all talking about it but people are still using room humidifiers?
There are also mister systems you can "inject" a spray pattern into your duct. If you live in an dry area this may work for you with no worries on fungus or mold. You can always counter act that with a uv light.
Are you in a 1 floor ranch style with a rooftop?
All you need is a return trunk to mount a powered humidifier on some place that's not going to freeze in the winter (like an interior wall)
I just did a tune up on a 7 year old natural gas furnace today. When I went to the top of the stairs to run the unit I looked at his contractor grade, RiteTemp t-stat. I looked at the customer dead in the face and asked him "do you like this thermostat?" He said no...
30 minutes later I finished my tuneup and he had a Honeywell Vision Pro 8000 on his wall and he loved it!
"That motor's done, he let the factory smoke charge out!"
I am having 2 Honeywell vision pro for the furnaces I have, one in the main floor and one in the bedroom up stair, when ever the unit kick in to function that is a "Click" sound, for the main floor I am careless about the click, but when is quiet in the bedroom, that click is very ignoring, it take a wile to get use to it. Otherwise this is a very good T-stat.