No, not too far-fetched but what is the likelihood that the perp would hang around and wait while MS rode her bike over to BW's house, drove over to Taco Bell and drove back to BW's house, then left BW's on her bike. How would the perp know she would be coming back to BW's and then would be leaving again to begin with if he was a stranger perp/serial killer? The scenario before MS began her bike ride home was pretty cumbersome imo for a stranger perp to have spotted her at Artmosphere and then continued to keep his focus on her after she got on a bike along with a male friend and began riding away.
Usually they lure the victim in or it's a quick random attack.
We know there are cameras at Artmosphere (that's how they know the time MS entered and left there) along with video that was taken by the band - they said it like that, 'the band'. Do they mean a representative of the band or a band member took it while they were on break? They mentioned specifically that the video was taken on the back patio area at Artmosphere.
Mickey and BW were planning to move to New Orleans very shortly. I did it when I was 19 for a short time. New Orleans has a draw if you live in Lafayette; it's like Lafayette's big sister. You want to spread your wings a bit in the big city. They were at the perfect age and time in their lives to do that.
What if someone they knew had done the same thing and headed back home to Lafayette for the performance at Artmosphere. Already knew the crowd and the routine.
I don't have any answers for your questions about the photos taken at Artmosphere.