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Title says it all.
I am struggling to find something which won't need fettling, but it could be my Google-Fu is lacking today.
Thanks.
Mudhugger FR? Fit the extension for a bit more coverage.
https://www.planetx.co.uk/i/q/FSZEDFM20/zefal-deflector-fm20-front-mudguard
I use one of these, fitted ‘backwards’ on my DT Swiss OPM forks. Plenty of coverage front and rear of the arch and nice and stiff so it doesn’t flop down on to the tyre.

Mudhugger (fat/wide) fits fine on my Manitou Mastodon, so I'd assume the standard one fits on a Mattock etc.
I have a mud hugger on my mattock and found that there wasn't really enough clearance kept jaming with a few leaves or mud. Ended up cutting a hole for the brace to sit into it works better but still very tight clearances.
Interested to see if anyone has found anything better ?
Mucky Nutz have a reverse-arch-style fender: https://muckynutz.com/MTB/face_fender_reverse