The reason that I just can't take that idea seriously is that, well, there at least was someone actually shooting, so if it was faked the way they would have to do it would be along the lines of "shooting at Trump, but intentionally missing". That would be a fairly dangerous move though, if your fake shooter's aim was off, there's the risk that it accidentally becomes a real assassination instead, and that level of risk feels out of character for Trump.

Further, were it staged, I'd expect it to be designed to advantage Trump as much as possible. Surely the "shooter" would be revealed to be one of the many demographics he riles people up against, or at least an outspoken democrat, and surely they would have played it up as much as possible throughout the election instead of having it done well before the final weeks and letting it get buried by the news cycle before people actually went to the polls.

He also surrounds himself with loyal but often incompetent people, and is an old man prone to saying embarrassing things. Would he really have been able to keep such a fake a secret even for this long?