Frame Rail Connectors

WRONG!!!!! The car (body) must be supported in a way that loads the suspension.

Or what? The sky falls? End of the world as we know it?

Take a look at some of the resto threads on here. A LOT of folks weld in frame connectors when their cars are on a rotisserie. I have yet to see a thread on this forum (or any other Mopar forum for that matter) about anyone installing frame connectors while their car was on a rotisserie and then not being able to properly align the body panels or suspension afterward. For that matter, I don't think I've ever seen a thread about anyone installing subframe connectors in any way that resulted in poor body or suspension alignment afterward. Suspension points on these cars from the factory were +/- 1/4", body fits were even worse.

I keep hearing this but nobody can point to any supporting documentation.

I haven't seen any either. I would say that on a rotisserie, with the drivetrain and everything else out of the car, as long as the body panels all line up you're good to go. I have in fact seen a restoration where the frame connectors were welded in with the car on a rotisserie while the car was stripped to the shell and while the car was "on its side" on the rotisserie so the connectors could be easily welded in. When complete the car had no fit or alignment issues. That's not how I would recommend doing it, but apparently it worked.

With the car fully assembled I would install the frame connectors with the suspension points loaded, OR the frame leveled with all the body panels aligned as desired.

If all the body panels are properly aligned, you're already ahead of what the factory did.