I use the foam padding that is often used in boxes at this scale. The GHQ Bunker Box comes with a supply of this foam, as do the hinged lid plastic boxes that the other US vendor uses to package their models.*
I snip the foam very thin. Then I apply some super-glue (any cyanocrylic glue should work). This glue sort of "melts" the foam, compacting it down a bit, making it form to the surface a bit, but then drying to hold it in place. A single small drop in one or two locations can even simulate tie-downs of a rolled net.
After the glue has dried I dry-brush the foam to the desired color(s).

Here are some of my M3 TDs painted up for Tunisia. The official load-plan called for the camo nets to be stored on the back of the track, but crews often placed it on top of the gunshield so it could be more quickly draped over the front when taking up a hastey firing position.

Some of the crews have draped the net over the front of the gunshield and even over the top of the driving compartment. This approach provided some measure of camoflage from the front, but still allowed the track to be driven and the gun to be fired.

The crews of T19 SPGs often stored their camo nets on the sides of the hull, as have the no. 1 and 4 guns in this battery, to allow them to access the rear door of the track more easily to re-supply with ammo.
Works well enough for rolled and partially-deployed nets. I have not tried it for a fully deployed net.
Hope that helps.
*GHQ used to use these same boxes, and since I have been collecting for a loooonnnnngggg time I have a supply "built up" (ie: cluttering up my garage).