Miss James, IMHO I think you are spot on. I think of GA hiding from CA to talk to LE and not wanting LA to know either, and his comments to LE and apologizing for CA's behavior and untruths to LE. And I think of how GA told CA that it was rotting pizza that caused the decomp odor (IMO to protect CA from the truth) and how CA took that and ran with it, to protect herself from having to admit it was human decomp which would mean the child was dead, in the trunk, and that her daughter had killed Caylee. And I think of LKL, and how nervous GA was when LK specifically asked GA about the smell. GA just couldn't tell the truth about what he thought in front of Cindy - and how he took a breath and then spouted off about the pizza. And I then think about the interview with NeJame in front of the courthouse. GA knew that what he said before the GJ would be secret and protected and CA would never find out. GA told the truth to the Grand Jury.
But as long as CA would hear what GA was saying, GA told lies that would be acceptable to CA.
And I think the reason was that GA was trying desparately to protect CA. CA was his livelihood, he didn't want the divorce she had been threatening him with. For GA, telling the lies was self-preservation. Protect CA from the truth at all costs, and put up a united front, and then GA would also be protecting himself. And he followed CA's lead.
He just didn't anticipate the LE interviews would be made public, and he never ever thought there would be a possibility that the GJ testimony would be released. GA told the truth when he thought he could, when he thought he had to, and when he thought he was protected by law.
IMO, GA knew when he first smelled the decomp odor at the tow yard what had happened. I do not think that GA or CA had anything to do with the murder/accident or any sort of physical cover up, i.e. moving or hiding the body. That was all KC.
JMHO