I like your theory, but it seems like a lot of coordination to me. I still haven't ruled out a solo effort. Here are a few thoughts:
Here are some of my general thoughts on Kip's cheating at the Boston Marathon.
1) Kip obviously changed outfits during the race. He could have simply shed the jacket and pants, but the hat change suggests that he had a clothes stashed somewhere along the course.
2)Don't think he could have biked or driven the course. It would be impossible to jump in at every 5k mat, Jump out, circle back to bike or car and get to the next point in time unless he biked the entire course. And we see from some of the photos that he is obviously not on a bike during the early stages.
3)So if the first two points are true, he would have to have someone helping him. We already know or at least suspect that his buddy Ben is in on this ruse. So it may be him or there may be others.
4)We clearly see photos of Kip at the 15k, 20k, and half and late stages of the race. This probably rules out 2 runners each doing a part of the course. Otherwise you wouldn't expect to see photos of Kip so early in the race. Plus the unusual splits make it unlikely that someone was really running the course.
...The only questions that this theory still leaves unanswered is why Kip appears to be going so slow in the 20k photo.
first, your point #2. Just because he didn't use a bike/car at every 5k/early in the race, doesn't mean that he didn't strategically use something like that at some point later on. For example, run the first 20k/half... take a single bike/car stashed just after the 20k or the half. Then drive/ride at least the next 5k, or if you need more of a breather, park it/get off to trigger the 25k split and drive/ride to the 30k'ish point. Then back to running. That would basically require running a half marathon in 1:25:30 (with a fade at the end), and last 7-10 miles or so. A nice breather in between.
Seems logistically easier to manage. No accomplice to gum up the works.
We know he had some kind of uniform change.
That 20-25k split keeps jumping out at me. His consistent 6:20-6:33 pace dropped off a cliff between the 20-25k points. Especially bad was between 20k and Half (8:34 pace).
Maybe he was going slow in the Jim Rhodes picture because he was starting to struggle before taking his "break".
IMHO, it would be really helpful to determine for sure which (if any) pictures were taken between the 20k&25k points.
In my opinion, wherever the big gap is between pictures is a good place to dig.