i don't see anything wrong with this...the interior could look really cool. you have my support...
question, where would you mount the blacklights? and 2 15" blacklights is a lot i think...2 of those light my whole room...maybe just 2 6" blacklights?
maybe mount one behind right your dome light, with side tabs so the light doesn't shine anywhere but down onto the passengers (i'd hate to have a blacklight in my view every time i looked in the rearview mirror, or if i was sitting in the backseat and had to look into a blacklight...and this way they won't be visible from outside) and one under the radio/heating controls, just above the cupholders? that should cover the front and back seats nicely, without overdoing it.

just some thoughts, good luck