[bbpwr]

i had to do this once. take a pressure washer and spend the day going over the marks should get about 80% of the marks off and the rest you can remove with a wire wheel on a grinder or a drill. yeah its a drag but it works

 

[bbpwr]

if i was in this situation i would talk to the person who is so ticked off over the marks be nice appoligize offer to try to pressure wash the marks off be sympathetic from the owners point of view assure them you regret what you did and that you did not know that it was a private rd im sure if you speak to them and do it oin the right way some kind of resolve can be reached.
kindness to ones anger can almost always bring about change . whatever you do dont blow them off you could get sued for much more in the end than just a repave on the road. . best of luck to you and i hope this all works out for you guys.