Although my favorite parts What do you think the hottest position is while running a train on a girl?
I think the positions when she can't tell which cock is pounding her asshole are the best.
1) Standing doggy against wall
It is best when the girl is wearing heals and would be even hotter if her hands were locked behind her back to add extra domination factor
2) My personal favorite: lying down doggy
For me the flatter agains the floor the better to pin her down while fucking her ass give maximum penetration. . No heels needed in this position but would be hotter if the girl is wearing lingerie with only access to the asshole.