Did you look at the simulated perforatied vinyl material? That could cover the base cab headliner. When I looked at mine, it is a shade of Grey. I believe Mopar used perforated headliner in truck cabs at some point. Not sure if that is available to make your own.
Thanks for the response. My wife and I visited a large fabric store yesterday and after looking through hundreds of upholstery fabric and vinyl rolls, bought four meters of an outdoor fabric with a tiny checkerboard pattern which I think will work fine and give a perforated look. Unless you look really closely it looks sort of light grey even thought it is made up of brown and white squares.