To actually answer your question, in looking at my Stryker walk around (over 1200 photos and counting) these "vents" all have louvers behind them, so yes, there is green underneath the mesh.



I visit the reset facilities for several vehicles on a regular basis (the Stryker reset facility at JBLM, Bradley Faciity at Ft. Carson, Abrams and Bradley at Camp Shelby, MI, JLTV at Fort McCoy)) and I can tell you, these guys don't waste a lot of time on masking when repainting - mainly lights and optic. (strangely they could have just removed these)



So if you are doing one in sand, they'd shoot the CARC straight through the mesh.

Refit facilities offer great diorama possibilities by the way. Great way to show off those resin Stryker engines by Legend...