Through all the effort of getting a second eevee and the impracticality it will serve you in the future. Ditto is easily the better choice. All you need to do is ride your bike back and forth the route the Day care is on and it can happen very quickly.
As an added note, Pokemon from different games tend to be more likely to breed. I recommend simply getting a traded ditto and you will have a 49.5% chance of finding an egg every 255 steps.