Good idea years ago when we didn't have any decent 12v fans. We do now. There are many decent 12v fans to chose from now that are quiet, have thermal tracking and come with LED's. I just bought a bunch of these for my 12v cooling projects;If you can find some old 24 volt computer fans they work great. By running them at 12 volts they are quiet and still move plenty of air.
Simpler solution;...Maybe invest in some sort of sheet metal to develop a shroud if I really wanna get crazy.
What do these things usually put out for power?