For a little background on the ship (the background that I know anyway), the ship was stolen by Jango Fett from a penal colony/planet (ala Kessel) set within an asteroid. The story pops up in "Bounty Hunter" the video game for Gamecube and PS2.
There are other Slave I's there and he does destroy them but for fear of pursuit. I believe I've heard the notion that his is the only Firespray Attack Ship, but other EU contradicts that and the Firesprays are not overly common, but there's more than one. X-Wing: Alliance for instance features a Firespray in it prominently (a character in the game that is a relation to the character you play has a Firespray as his personal ship for instance).
The paintjob, actually, is exactly as it appears in Episode II (Not to rain on your custom idea... By all means, it sounds great so I say go with what you want to do). The color pattern to it in AOTC is that of a Republic "Police" ship (or Republic Standing Military perhaps) which is what it basically is I guess... Jango just hasn't painted it up yet. And of course Boba paints his to match his armor.
The planet's dreary, but it's still a Republic controlled instillation so there's an element of military "cleanliness" as well. It's a great game with the full story that explains Jango's background and how he came to be the choice for cloning.... I recommend playing through it entirely just for the storyline.
BTW, Airbrushing sounds fantastic... I'm curious to see how the paintjob turns out then... For insignias, I'd almost lean away from painting (if you're using sorta "known" emblems like the Imperial one or anything like that), and instead print the insignia (often can be found online somewhere) out on sticker paper, or water transfer decal paper... That way the painting detail is minimized a bit. Kill markers would be really neat on it too I think (just a thought).