An alternate approach is to heat fix the G- to a glass coverslip, sputter coat, and examine. I've had excellent results air drying from hexamethylsilizane at room temperature. Peldri will also work if you've got any left. Filtering through a filter works fine. No fix and air drying will almost certainly change the shape and size of the bacteria.
Polycarbonate membranes handle the solvent very well.
They dry in minutes and you can quickly afix them to stubs and sputter coat. Then sputter coat Will give you much better results than heat fixing and air drying.