To the best of my knowledge, Scamp has always had a non-opening, compound curve, plexi front window.
Someone really clever would make them and sell them to Egg owners.
That said, it wouldn't take too much cleverness to come up with a wooden or
fiberglass insert to change the compound curve flange into a flat mounting surface for a crank or slide window. I would expect the gravel shield to keep road rain out (my old Jayco, flat in front, had crank windows, a gravel shield and didn't leak).