Fluorescent lights are not a problem either way. There is some research being done on snakes and the effect of day cycles. The initial evidence calls into question the importance of light so as it does no harm there is no reason what not to provide a day night cycle. Royals (balls) in the wild have extensive records of being out and active in twilight (evening and morning) and have been recorded on roads warming during this time. This is true for many snakes world wide, blue hour is often a favoured snake hunting time.

Aside from this the use of fluorescent lights add to ambient air temps in a real and recognizable way. This aids thermoregulation. They are far cheaper than some of the alternative and in my current testing more effective.