1/12 pan wheel arches

[Dal]

Hi Folks

As a recent noob to 1/12th pan I have received my first painted body today.

Just need some help with how to cut the arches, specifically the rear arches.

On my 1/10th touring shells, I would line up the axels of the car with the wheel-arches and then make small pin sized incisions in the plastic where I would then later on use a compass cutter to stick the center pin into.

On my 12th bodyshell, the front wheel arches have masking tape at the center, so I'll be able to work out the alignment, I can also see the wheel arch mold line so I can follow it.

The rears though are completely solid in paint, I think im gonna have to mount he body and eyeball the rears, is there any other way to do this? I want nicely aligned wheel arches (rear).

Thanks in advance!