need extensions for the new tires

[jeffs blackjeep]

i have been looking for fender extensions when i get my new tires (12.5" wide with spacers) and want to keep the boys (and girls) in blue happy. the fenders on the JL aren't flat underneath and its a bit of a challenge to add a 4" wide piece of plastic to cover the part sticking out.
i've looked at what was online, but australia has different fenders to the u.s./canada versions and the other is a tad overprised...any thoughts would be appreciated on making some.

cheers!!!