The upside-down plates: She did that so if her innocous car was captured by a traffic cam the plates wouldn't be read by the scanner.
When she was being interviewed by the detective and was denying she was in Mesa, she told him to check the red-light camera, because if she had been there the camera would show her car. But then the detective says "But Jodi, it would only take a picture if you ran a red light."
She was thinking that the absence of evidence would prove she wasn't there. If they checked the camera and ran the plates they would have gotten nowhere with a plate that couldn't be read.
At first I thought maybe it was to get pulled over and establish an alibi but she could have been pulled over in Mesa and blown any alibi. Because she brought up the "check the traffic cams" that makes me thinks she thought she was beating the system w/ the upside down plates and they were upside down while she was in Mesa, not switched after the murder so she could be pulled over in Utah. I think after the violent murder she wasn't thinking about the plates. If I'm right, it goes to pre-meditation.
(sorry, not very articulate this morning, hope that makes sense and it is just my best guess)