My suggestion would have been similar, just look for a small battery powered clock that you can then place where ever you want, and as an added bonus, you wont have to reset the time when ever you take the car battery out. Should be able to find something decent for not much money at all, have a look at a large auto parts store or otherwise try ebay!You know You could buy a cheap wrist watch with big display and stick it in front of original. This way you get a chance to be creative!!! You also get added features like seconds and date. Now thats a mod worth doing!!!
Install a flux capacitor and time will be irrelevant.