Finally got down to it and knocked together something to serve as camo netting. It's a petticoat mesh, folded and held together with some glue.
The center one in this pic was my original prototype. It turned out... less than optimally, what with the blotch of static grass. The other two are, I think, improvements.
Started life as sub-$2/yd petticoat mesh from the fabric store. I cut it to fit and folded it. The original assembly was a pain: superglue didn't behave particularly well, and plastic glue was useless (in retrospect, this is expected, I think). Eventually settled on PVA and good ol' foam tack glue in the the final form. After getting the corner glued and it was able to lay flat on the model, it was time to apply the flock. Inspired by breaded meats, I "battered" the mesh (not completely) with Liquitex matte medium (it has a really good consistency for this, although watered-down PVA might work if you can get the mix right), and dredged it in flock.
Since the mesh on these designs was going to be anchored at the turret as well, I decided to stop trying to glue four corners and instead cut it to fit with one glue point.
Important note: it helps to wrap the model in plastic wrap ahead of time, especially if this is going to be an aftermarket attachment to the model, applied after painting.