A 13mm flex socket works for me. Long extensions through the K-member. Can be easier if a buddy turns the ratchet while a 2nd person guides the socket onto the bolt (by feel).
When it comes time to re-install, lightly tape the bolt to the socket to aid in getting it started. Once started, remove the tape.
Once you have done it a few times, then it is easier to visualize the location of the bolt and it will go much quicker/easier.