I think an earlier article states that RG was hired to work at a cabin 5 hours away and had been commuting back and forth. So he probably knew the routes and hidey-holes pretty well and wanted evidence as far away as possible. Remember that getting caught speeding was not in his plan- he probably was going to say that he was home all night or something.
I am sure he did get back at 6:30. The oldest child is 10. Old enough that if she woke up without parents, she would call grandma and grandpa or 911. Also, he might have planned to be back earlier and realized coming home at 6:30 am, people would see his car coming back- most people are up getting ready and leaving for work around then. So he couldn't lie about the time too many witnesses. JMO
I am sure he did get back at 6:30. The oldest child is 10. Old enough that if she woke up without parents, she would call grandma and grandpa or 911. Also, he might have planned to be back earlier and realized coming home at 6:30 am, people would see his car coming back- most people are up getting ready and leaving for work around then. So he couldn't lie about the time too many witnesses. JMO