Can I extend the epoxy out past the Garage door?
No we don't recommend that. The epoxy should end at the inside or outside edge of the garage door. If you want to finish that little strip of concrete outside the door it's best to take a small sample of the epoxy to your local paint store and have them match it with some inexpensive outdoor concrete paint. This way when the weather and elements beat it up you can recoat it with inexpensive paint rather than expensive epoxy that is not designed for outdoor use. We make outdoor epoxy but it's not worth the expense for such a small area.