Cardboard Lattice...

[Steamtrains]

OK...So I'm working on the peninsula for the layout. But before getting too far ahead I need to finish up some unscenicked portions of the layout that will be hard to access (or impossible) once the peninsula is in place. Since there are some "wide-open" spaces I decided to use a cardboard-strip lattice as a base for the scenery. My question is..Does something cover the lattice to "smooth" it somewhat before applying the plaster cloth? I fear that if I place the cloth directly over the lattice I'll have some really "squarish" look to the ground...
Any ideas would be most welcome...