Before we used sqeegees it was all leather and scrim, if the windows were quite clean you could get away with scrimming only.
You can do a perfect job using scrim only, but it has to be clean and damp, it would need washing frequently, in clean water without any detergent, it was wringing them out dry enough to use that was the fun part, You would be waving the scrim about like a demented Injun sending smoke signals.