I wasn't sure where to post this, but open to moving it elsewhere. I've been creeping options to replace the Whelen 900 lights and as cool as it'd be to use their $300+ replacement LED units, that isn't in the cards (read: the wallet haha). The best option I've seen so far is Abitibi (David)'s modified loaf pan. I have been thinking about the recessed metal cabinet idea since seeing his, and drew this up Friday. I'm getting quotes in both 1/8" aluminum and 16ga steel, leaning toward the latter for cost.
For reference, here are the lights I bought awhile back: