[kickstarts]

with a hammer.... lol

cut a piece of tube around the fork tube then cut and weld it in the fender and grind and shape it. or use the piece of tube/heavy pipe to hammer the fender into.

I'd do exactly this^^^. Get some exhaust tubing the correct diameter(raw, not coated), cut the area out and weld the tubing in. That should be your cleanest option.