A lot of guys do chop and can look great but I wouldn't chop my oem mudguard . Since the R3 has been discontinued , standard bikes will eventually increase in value and a standard mudguard is expensive to replace.
Better to look for a fender from a broken bike , member @albertaduke is currently offering one here for a price you won't beat .
Alternatively ,on the UK ebay site you can buy fibreglass ones .
The fender frame will need altering but I don't see that as being a big job . There are many posts and pictures on here of fender chops !