I will say, if the second shooter is the one that hit Trump, he probably wasn't on the water tower; I don't think the trajectories would line up.

I was/am suspecting a second shooter (as I've said, assuming the whole story about the officer on the roof is true, at least), but after looking at and thinking about the water tower theory more, I'm not sure I buy that specific part.

As for witnesses, people are hyped up, and trying to make sense of things. Gunshots also create echoes, and the tower will catch some of that. People are trying to make sense of a dramatic situation that just happened, and the water tower would be a prime location, so they may simply be subconsciously building a scenario that makes sense to them at the time.

If there was a second shooter, and if the second shooter is the one who winged Trump...I don't think he was in the water tower...which means you're now talking about a second and third shooter. Which is just getting more absurd.

If there was a second shooter, he was either farther out, or in the building that Crooks was on top of. Again, all this is just my theorizing, of course.