Essentially agree with the others, don't worry about Step 2. You have an above average Step 1, Step 2 is not going to come back in time to have a signficant impact on your app. I don't think the purpose of an away rotation is to get a big name letter. Away rotations usually do not give the applicant enough time with the big names. They are going to be writing a letter after working with you for a week at the most. It shows in the letters, believe me. PDs would rather see a letter from someone who has really gotten to know the applicant and that is difficult in an away elective in July and August. You need that letter in hand in late August, it's just not enough time to develop a good relationship.
I would do an away rotation to be helpful for matching at that specific program. If we liked a student who rotated with us, they will automatically move up the list. That said there can be downside to an away as well. If you show up and hold up the wall, constantly text on your phone, etc you will move down.