I have experienced the same cross-wind problems on bikes that weren't designed for fenders (Rivendell, Mercian), especially if they also were equipped with a handlebar bag. However, Singers don't seem to suffer the same way, even with the handlebar bag. Something about head angle and fork rake? I don't know enough about bike geometry to determine, I just know that some work better than others.
Out of curiosity, is there a WEB site that night list the geometry of Singer bikes? This is not the first time I have heard this said about them. But damn, they are EXPENSIVE!
Thanks,
Mike Natale in Richmond