If I'm reading you right you are talking about the bottom aft corner of the door being a sharp point that your dog (like mine) wants to scoot under/around to get in the door as soon as it's cracked open.
Well I don't have a good idea other than to say that our dog has learned to duck pretty good, and hasn't had a problem yet.
Maybe some of that automotive door edging (the stuff to keep your door from making dings in the neighbors car), that wraps around the edge of car doors would be small enough to fit on the door without causing too much interference and then it would have a thin plastic cover. Might be too thick though.
http://www.amazon.com/Full-Size-Clear-Shape-Guard/dp/B00UG2QYSY/ref=sr_1_2?ie=UTF8&qid=1459473550&sr=8-2&keywords=car+door+edging