Both my girls were posterior. With DD1 I was induced with the drip and had an epi , but I was fortunate enough to not be stuck on the bed for the entire labour. With DD2, labour started on its own and I had no drugs. I birthed both girls on my back and I both girls were born within 10 minutes of starting to push and I did not tear with either of them. For me personally, birthing on my back was the easiest and less painful way.
Good luck!