Slightly longer bolt and a nice wide spacer looks better than a couple of fender washers. Not unusual. Slight welding may shrink radius slightly.

Tim

Thanks Tim and Bruce!  I'm understanding that a gap in this area is not uncommon.  I've got some snowcat track rubber belting that I can cut to fit and fill the gap, and I may do that in the end.  I know it left the factory without that gap, but perhaps it was always a poor fit and destined to fail...I can close the gap with a ratchet strap around the seat post and blocks inside the fender, but after releasing the tension on the strap it relaxes back to the gap!

I would check and adjust the ridge arc of the fender, just a minor shrinkage or dent of the fender somewhere along the edge may make the gap you have there. Make a cardboard template of the front fender ridge, front and rear should have the same bow. The fender is welded at the edge so i suspect some shrinking may have happened, expanding the edge with hammer and dolly may fix that.

The fender should fit without gap, or at least shimmed, tension at that seat plate bolt will crack the fender in time.

Harry, I usually repair splits in fenders by bronze welding/brazing, using a piece of sheet metal for larger repairs or a washer for split mounting holes. Bronze causes less distortion as it has a lower melting point, and retains flexibility, so cracks are less likely to reappear. Mind you, I am not a professional sheet metal guy, but thats what the old welders did when I was a youngster. 

Ha, not the kind of old welders I was thinking about, Harry. How did you fix it ? Might get away with just drilling the end of the cracks and tapping an aluminum plug in .